An Apology to my Readers

I just wanted to apologise for my lack of a blog, recently.  As it happens, I have obtained unexpected temporary employment - lecturing on Forensic Science at my local college.  This means that I am fully occupied preparing lectures, teaching etc.

 

 

I will be blogging again when my employment ceases - at the moment this is the end of October.

 

 

So while I am away helping to prepare the next generation of would-be forensic scientists, why not get that crime novel finished? When I start blogging again, you can share your link with your fellow readers. 

 

 

In the meantime, here is a link to a case where a review of the forensic evidence by a TV programme resulted in the conviction of the real perpetrator.

 

 

Rachel Manning Murder Case

 

 

I hope you'll stop by again when my blog returns.

5 Crime Scene Tips

I don't know if you have come across 'Forensic Magazine' online, but it is a great resource for writers, students, and anybody who wants to know more about forensic science.

 

I particularly like their 'Crime Scene Tips', so I thought I would share some of them with you in this blog.  There's no particular theme, but I hope you find them useful and/or interesting.

 

1. Avoid Contamination

 

A golden rule of crime scene investigation is the control of contamination and cross-contamination.  Here is the link to a list of good practice points:

 

http://www.forensicmag.com/articles/2013/07/control-contamination#.UgoVBnY1jIU

 

Many wasted investigative hours were spent in the so-called 'Spy in a Bag' case owing to contamination.  DNA found on the victim's body was not a significant lead in the case, as the police first thought, but originated from one of the scientists working at the scene.

 

Here are the details:  http://www.standard.co.uk/news/crime/forensic-dna-blunder-hindered-spy-in-bag-investigation-for-a-year-7603447.html

 

2. Finding Evidence Using Fluorescent Light

 

This tip is especially relevant if you are a screen writer. In the link you will find a video demonstrating how to use fluorescent fingerprint powder and specialized lighting conditions to locate evidence.

 

http://www.forensicmag.com/videos/2013/06/find-evidence-using-fluorescent-light#.UgoZwnY1jIU

 

3. How to Process a Fire Scene

 

The destructive nature of fire makes processing the scene very challenging.  Here is the link to the checklists of procedures that fire investigators should follow.

http://www.forensicmag.com/articles/2013/07/processing-fire-or-arson-scene#.Ugo9bnY1jIU

In the UK, Dyson Allen, 19, was recently convicted of the manslaughter of three small children and their elder brother, who tried to rescue them. 

Although Allen maintained that the fire had started accidentally, the forensic scientists who examined the evidence found that it had been started deliberately.

Here is an account of this tragic case:

http://www.bbc.co.uk/news/uk-england-lancashire-23416352 

4. Arson Scene Hazards

This tip is related to no. 3 and should be common sense to experienced investigators, but maybe not to a rookie.

http://www.forensicmag.com/articles/2013/03/arson-scene-hazards#.UgpBc3Y1jIU

5. Documenting a Vehicle Death Scene

Sadly, people die in cars every day, as a result of road traffic accidents.  Inhaling exhaust fumes while inside a car is a common method of suicide,  Perhaps a body is found inside a car on a parking lot and the cause of death is not immediately apparent.

Whatever the situation, here is an account of what the scene examiner should do when processing a car containing a body.

http://www.forensicmag.com/articles/2013/08/documenting-vehicle-death-scene#.UgpEcHY1jIU

Here is a link to a report of suicide in a car in Shanghai, China.

http://www.globaltimes.cn/content/796019.shtml#.UgzpyHY1jI

Thank you for continuing to read my blog.  I'll be back in two weeks time.


 



Asphyxiation - Murder, Suicide or an Accident

When a person is unable to breathe properly, oxygen cannot reach the tissues and organs of their body.  Without prompt medical intervention, their body becomes starved of oxygen and the person dies.  This is asphyxiation. 

 

There are three main categories of asphyxiation:

 

1) Suffocation

 

A person suffocates because oxygen is unable to get to the brain.  Examples of suffocation are drowning, smothering, choking on food and being in a confined space with elevated levels of carbon monoxide e.g. faulty gas fire in a living room.

 

2) Strangulation

 

Strangulation occurs when the blood vessels and airways in the neck become closed. The main causes of strangulation are suicidal hanging and homicidal ligature strangulation, although both causes can be accidental.

 

3) Chemical Asphyxiation

 

Gases such as carbon monoxide or hydrogen sulphide (found in sewers) prevent oxygen from being released to the cells inside the body.  Without oxygen, the cells cannot function and the person dies.

 

I'm going to concentrate on strangulation in this blog.  It is a popular means of killing off characters in crime fiction, but can give you a window of opportunity to save their lives, if your plot demands it.

 

Hanging

 

In the second half of the nineteenth century, a more 'humane' approach to judicial hangings was adopted in the UK. This was achieved by accurately calculating the drop based upon the prisoner's weight.

A prisoner's neck could be broken by allowing them to fall at a pre-determined distance (the drop). The momentum of the drop jerked the head back.  If the knot of the noose was placed to the left of the chin, this would cause the second and third vertebrae to be severed and death would be 'instantaneous'. 

 

If the drop is too short, death is by strangulation.  In some countries with a system of capital punishment, this is the fate of a number of prisoners.  It is usually the fate of the suicide victim also.

 

If a person hangs themselves with little or no drop, they will be strangled slowly.  It is an extremely painful death.  The victim is often found in a kneeling or sitting position.

 

The mechanism of death

• The noose becomes tighter and tighter until the carotid arteries and jugular veins   become closed or 'occluded'.

• The occlusion of these blood vessels causes a severely reduced flow of oxygenated blood to and from the brain.  This is called cerebral hypoxia.

• The weight of the person's body forces the larynx and base of the tongue upwards, so that the person is unable to breathe and is asphyxiated.

Timing of the event

• From 1 - 3 minutes after the person is suspended, they may exhibit signs of physical struggling.

• This is followed by a period of quiet.

• After the person has lost consciousness, the body may exhibit spasms, which are nervous or muscular reflexes.  There will be a final heaving of the chest. 

• Brain death occurs around 6 minutes.

• The heart will stop beating after 10 - 15 minutes.

Appearance of the body

If the carotid arteries are occluded before the jugular veins, the heart will stop rapidly.  The face will be pale and bluish in colour.  There will be no petechiae - small red spots caused by broken capillaries.

If the jugular veins are occluded before the carotid arteries, the face will become engorged and livid (dark red) as the brain becomes filled with blood that has nowhere to go. 

Petechiae will be present inside the mouth and lips  and in the eyelids, where capillaries have broken owing to the excessive pressure.

The tongue may protrude.

Bruising

The rope pressure will cause an inverted 'V' -shaped bruise on the side of the neck.

Here is a link to a scholarly article describing a variety of suicides by hanging. 

WARNING: At the end of the article there are four black and white photos of a body hanging from a tree.

http://www.indmedica.com/journals.php?journalid=11&issueid=131&articleid=1738&action=article

Accidental hangings

Accidental hangings are uncommon.  A young person may be playing with a rope in a tree and somehow manages to become entangled, with tragic consequences.  This happened many years ago to a family member.

Accidental hanging during erotic asphyxiation is occasionally reported in the press.

 

In both instances, the circumstances of the hanging will clearly point to accidental death

Homicidal hanging

Homicidal hanging is very rare indeed and a challenge for the forensic pathologist.  Invariably, other marks will be present on the body that will support the view that the deceased was murdered and did not take their own life.

 

Here is an abstract from a scholarly paper describing such a case.

 

Murder by hanging





Strangulation

 

Strangulation by hand, or by using a scarf, cord or something similar, leaves more evidence on the body than suicidal hanging.

 

Invariably, the murderer will use more force than necessary to kill the victim.  This results in deep bruising, abrasions and contusions on the neck.

 

The victim is likely to be fighting for their life and will struggle vigorously at first.  This will cause damage to the neck, both internally and externally.  For example, the hyoid bone, which lies at the base of the tongue, may be fractured, as a consequence.

 

The victim's face will be congested and livid (dark red) owing to occlusion of the blood vessels.

 

The bruise on the neck from the scarf/cord will be in a straight line and not 'V' - shaped, as in hanging.  There may also be additional bruising at the base of the neck, caused by the pressure of the murder's hand.

 

Strangulation is almost always homicidal.  Accidental strangulation is rare but can occur when a piece of clothing or jewellery becomes entangled in machinery or a moving vehicle, for example.

To finish this blog, here is a link to an article about accidental strangulation which has a happy ending.



Survival from accidental strangulation from a scarf

 

I hope to see you back here in two weeks time.  Thanks for stopping by.

Abdominal Trauma - life or death for your characters

Diagnosing an injury within the abdominal cavity can sometimes be very difficult.  Fat and muscle can mask injuries and conceal bleeding.  The task may be made more complicated if the patient is in a coma or has other injuries.

 

If you are looking to create a life or death situation for one or more of your characters, injuries within the abdominal cavity - known as 'intra-abdominal injuries' -  are a good place to start.

I've compiled the following brief guide to help you.

 

Inside the Abdominal Cavity

 

The organs of the abdominal cavity are the stomach, liver, gall bladder, spleen, pancreas, small intestine, large intestine and the kidneys. 

 

These organs are either 'hollow' or 'solid', apart from the kidneys, which are both - the bean-shaped portion of the kidney is 'solid'; the blood vessels and the ureter (which carries the urine away from the kidney) are 'hollow'.

 

Blood vessels associated with these organs are, of course, also 'hollow'.
 

Damage to the Hollow Organs

 

The basic patterns of injury to the hollow organs are:

• Cutting or tearing of the  blood vessels, which then haemorrhage.

• Cutting or tearing of the blood vessels that leaves the associated organ without a blood supply.  This causes gangrene, where tissues die that are closest to the injury.

• Leakage of body fluids from a perforated hollow organ..

 

Damage to the Solid Organs

 

The basic patterns of injury to the solid organs are:

• Cutting or tearing of the blood vessels, which then haemorrhage.

• Cutting or tearing of the blood vessels that leaves the associated organ without a blood supply.  This causes necrosis or 'death' of the organ in extreme cases. 

• The tissues of the organ shatter, resulting in haemorrhage.

• Leakage of body fluids from a damaged organ.

 

Types of Injuries to the Abdominal Cavity

There are two types of injury - Blunt Abdominal Trauma and Penetrating Abdominal Trauma.

Blunt trauma will be something like a kick or an impact during a car accident, for example. 

Penetrating trauma can be a stab wound, a gunshot wound or being impaled on railings, for example.

Examples of Injuries caused by Blunt Trauma

i) Hollow Organs

For a crime writer, blunt trauma to the hollow organs of one of your characters can have a dramatic impact, because the symptoms may not appear immediately.  Your character can be walking and talking and then suddenly collapse  - and maybe die - without warning.

A blow to the abdomen may appear trivial initially, but inside the cavity, major damage may have occurred to the hollow organs and associated blood vessels.

Symptoms such as pain or bloating may not appear immediately after the blow, but by the time they do appear it may be too late.

Damage to the colon, which is the main part of the large intestine, will cause faeces to leak into the abdominal cavity.  This results in peritonitis if left untreated, which can be fatal.

Here is a video showing a doctor talking about the symptoms and causes of peritonitis.

If associated blood vessels are damaged, then they will haemorrhage, resulting in the collapse and possibly death of the victim.

Damage to the small intestine  and its associated blood vessels may also cause peritonitis and haemorrhage.

ii)Solid Organs

If the blunt trauma is inflicted to the right side of the lower ribs or abdomen, then damage to the liver is likely to occur. 

For mild to moderate trauma, the damaged parts of the liver will be cut away and the blood vessels will be sutured to stem the blood flow.  However, major trauma may cause the liver to 'explode' and the victim is unlikely to survive because of the intensity of the bleeding.

A ruptured spleen occurs with left-sided trauma.  The victim may not be aware of the damage that has been inflicted on their organ.  He or she will initially feel light-headed and their skin will become pale.  They may collapse because of blood loss.

Bleeding may stop spontaneously or the victim may lose so much blood that one or more transfusions are necessary to ensure his or her survival.

Here is a video showing an operation to repair a ruptured spleen after a car accident.  WARNING: Some people may find this video rather gory.

Examples of Injuries caused by Penetrating Trauma

The results of injuries caused by penetrating trauma are similar to those produced by blunt trauma.  A knife can slice through an organ or blood vessel and cause a haemorrhage.

A bullet can rip through the stomach and liver and ricochet off a rib, which causes it to change direction and perhaps enter the spleen or pancreas.  Alternatively, your character may only suffer a relatively minor injury because the bullet missed all the major organs and blood vessels.

Here is a video of an operation to repair an intra-abdominal injury caused by a bullet.

WARNING: Some people may find this video rather gory.

Diagnosis of Intra-Abdominal Trauma

The problem for the medical team is that a high proportion of major abdominal injuries do not have significant symptoms or physical findings beyond a pain in the abdomen.

The patient, or somebody who was with the patient, needs to supply as much information as possible about the incident, as certain injuries will be more likely in certain situations.

If there are cuts and bruises in the abdominal area, they may indicate a deeper injury.

The doctor will press in on the abdominal wall and release it suddenly to see how much it hurts the patient.  If the patient has peritonitis, the sudden release will cause severe pain.  The patient will require emergency surgery.

If the patient's abdomen is visibly swelling, it means that they are haemorrhaging and will require emergency surgery.

Here is a video showing emergency surgery being carried out on the mesocolon (the tissue that attaches the colon to the dorsal abdominal wall) after a car accident. 

WARNING:  Some people may find this video rather gory.

Other investigations include washing out the abdominal cavity with saline fluid to see whether there is any blood, urine, bile or faeces there, which indicates a lacerated organ. 

Alternatively, the patient may have a CT scan to see whether any of the organs are lacerated.

With blunt force trauma, in particular, the patient will be closely observed for the appearance of symptoms requiring treatment or changes in their symptoms, until the medical team are sure the patient is not severely injured.

I hope I have given you some ideas for either killing off your characters or bringing them back from the point of death - or maybe even allowing them to be completely unscathed by their experience. 

Don't forget to share a link to your book in the Comments section below.






 

 

Fingerprints v DNA



The ability to identify a suspect  from fingerprints left at a crime scene has been possible for more than a century.  Fingerprint evidence has one big advantage over DNA profiling - it can identify an individual.

 

Here is the reason why a DNA profile cannot categorically identify an individual.

 

A set of components or 'loci' on the DNA molecule is used to generate a profile.  These particular loci have been chosen for forensic purposes because they are known to show considerable variation between individuals.

The loci essentially represent a sample of a person's complete DNA profile. 

Relatives will share some DNA, of course.   However, there is a theoretical possibility that unrelated people will share the same DNA because the profile is, technically, a sample and not the complete profile.

 

Therefore, a DNA profile generated for forensic purposes will not be unique to an individual.

 

 

Photo courtesy of www.all-about-forensic-science.com

 

If the DNA profile of a suspect matches the profile generated from a crime scene stain, the scientist will express their opinion as to how likely it is that somebody else's DNA would match the crime scene stain.

 

If there is no reason to think that any of the suspect's relatives could have left the crime scene stain, then the scientist will say (in the UK) that if the DNA match between the suspect and the crime scene stain came from some unknown person unrelated to the suspect, the probability of a match would be one in a billion.

 

In other words, it is highly unlikely to be anybody other than the suspect's DNA at the crime scene - but the scientist does not state it actually is the suspect's DNA.

 

So, although DNA evidence remains a hot topic in forensics - and DNA profiling is highly discriminating - good old-fashioned fingerprint evidence is still able to attract research funding, particularly in relation to latent or 'hidden' prints.

 

Although there are a number of techniques to enhance latent fingerprints, only 10% of those left at a crime scene contain sufficient detail for identification.  Put another way, 90% of latent fingerprints found at a crime scene cannot be used as evidence in court.

Is anybody addressing this problem?  Well, yes they are.

 

I want to share an article with you about a new way of visualizing latent fingerprints on metal.

 

Gun and knife crimes are the scourge of the 21st century.  This new technique is particularly applicable to these offences, as knives, guns and bullet casings all have metal surfaces.

 

Here is the link:

 

http://www.sciencedaily.com/releases/2013/07/130702202907.htm

 

The researchers used colour-changing fluorescent films to enhance latent prints on metal surfaces.

 

Although the technique is still at the experimental stage, it looks very promising for the future.

Advances in DNA may have revolutionised forensic science and crime scene investigation, but there is always room for looking at old methods with new eyes.  Maximising fingerprint evidence will always be high on the list of research projects for the foreseeable future.
 

Which areas of forensic science would you like to see evolve in the future?  Do you think the advent of new techniques make creating crime fiction easier or more difficult? 

 



Location of Clandestine Graves - clues from plants

 

Murderers do not always give up the secret of where they have buried their victims. 

                                                                                         

Keith Bennett, 12, was killed in 1964 by Ian Brady, the so-called Moors Murderer.

 



 

Keith was one of five children tortured and killed by Brady and his girlfriend Myra Hindley in the 1960s.  Keith's burial place is still a mystery.  His mother died last year without ever knowing where her son was buried.

 

For a comprehensive account of Brady's and Hindley's crimes click here.

Advances in Search Techniques

Undoubtedly, the best way of searching for clandestine graves is to employ a team of experts, each of whom is a specialist in a particular forensic investigative method.

 



Investigative methods in forensic geology, botany, entomology and chemistry are becoming increasingly specialized.  Innovations in remote sensing tools e.g. thermal cameras have added another dimension to the search process.

In addition, portable soil chemistry equipment is much more sophisticated now.  Near-surface geophysical devices and mapping instruments can also play their part in clandestine grave location.

Here is a link to an article which discusses new technologies and procedures for the discovery and recovery of buried victims.

http://searchfortruth.info/sites/default/files/Forensic_Investigation_Clandestine_Graves.pdf

Plants as Indicators of Clandestine Graves

Despite the availability of the various new techniques discussed in that article, the value of plants as indicators of the location of clandestine graves is still relevant. 

In a previous blog, we saw how pollen was a major factor in determining the location of the bodies of Derek and Eileen Severs.  Now I want to consider the use of whole plants.

General Soil Disturbance Indicators

Digging a grave - even one that is shallow - produces significant disturbance to the local environment.  Besides destroying the primary root structures of the plants, the act of digging also causes the layers of soil to become redistributed.

Soil layers with poor nutrient content may end up on the surface.   This results in either little or no plant life, less dense growth or growth that is smaller and newer than nearby vegetation.

Digging a deep grave may disrupt layers of soil with differing levels of water retention. 

Depending on the soil composition, opening up the soil structure will either allow for greater water retention or cause more evaporation of soil moisture. 

Over time, more water-retentive soil will produce vegetation that is more lush than that of the surrounding area.

Where the soil is losing moisture, the vegetation is likely to exhibit more browning of the leaves than nearby vegetation.

Plant Succession Clues

When an area of ground is disturbed by digging a grave, plants will colonize the area in a set pattern of succession.

The first plants will be the 'pioneer' or 'opportunistic' species.  These will usually be grasses and weedy species.

These will be followed by long-lived perennials and finally, small shrubs and trees, known as 'climax' vegetation.

The rate that a disturbed area is recolonized will depend on the amount of light and water, the temperature and the soil conditions.

It is possible to predict plant successional stages for some habitat sites.  If a localized site exhibits different successional stages from the surrounding vegetation, then this is a good indicator of a potential grave site.

Another clue is the lack of species diversity in the localized site compared with the surrounding vegetation.

Fungi as Indicators

Certain fungi are closely associated with the presence of a decomposing corpse.  Ammonia fungi and post-putrefaction fungi provide visible markers of likely grave sites.

Estimating Time of Disturbance

Plants that are growing on a site can also provide evidence of time since the last disturbance.

The act of digging and refilling the grave with soil produces a seedbed in which new plants can become established.

For example, winter annuals such as the purple deadnettle, Lamium purpureum, germinate in autumn and die the following year after flowering.

 

The presence of the purple deadnettle in a localized area would mean that the soil was last disturbed in mid-autumn or earlier in the previous year.  If the soil had been disturbed later than this, the small seedlings would have been destroyed.

This data may correlate well with the dates in which a missing person was last seen alive.

Studies have shown that disturbed plots can remain visually different for up to five years.  However, changes in vegetation patterns do not necessarily mean that a buried body is present.  It is the soil disturbance that creates the change; not the presence of a body.

A Grave Site Revealed

I started this blog by highlighting the still unknown location of Keith Bennett's remains.  One murderer, did, however, finally reveal where he had buried the body of his victim and the family were able to have closure.

                                                       

Shane Fitzpatrick killed David Guilfoyle (pictured right) in 2005 in a fit of jealous rage.  Seven years later he revealed that Guilfoyle was buried in a shallow grave in a local beauty spot. 

Police took Fitzpatrick from his prison cell so he could show them the location of Guilfoyle's grave. 

A search revealed human remains, which were subsequently identified as those of David Guilfoyle.

Here is an illustrated article about the case.

http://www.dailymail.co.uk/news/article-2299833/David-Guilfoyle-Businessman-body-lay-shallow-grave-7-years-beaten-dead-love-rival.html

                                                                                                            

Just to let you know that I'll be blogging every two weeks until September, when I'll be back on a weekly schedule.  My readership is growing steadily, so do, please, leave a link to your book in the Comments section.

 

Invitation to Murder - The Murder of Alan Street

On the night of 19th December 2008, Alan Street was enjoying a few drinks in Burnley, in the North of England, when he met up with brothers Alan, Ian and Mark Palmer.

 

Here is CCTV footage from that night, with each identified individual marked by a red arrow. 

 

 

At the end of the footage, a man identified as Peter Leonard is seen talking on his mobile phone at a petrol station.  The person on the other end of the call is Alan Palmer.

 

Ten months later, Alan Palmer and Peter Leonard will be sentenced to life imprisonment for the murder of Alan Street. 

 

Another man, Kieron Davison will be sentenced to a minimum of eight years for manslaughter. 

 

Ian Palmer will be found not guilty of either murder or manslaughter.. Mark Palmer will not be charged with any offence.

Invitation to Murder?
 

After Street and the Palmers finished drinking, he and Alan Palmer (and possibly Ian Palmer) returned to Alan Palmer's house in Stockbridge Road, Padiham, which is a few miles from Burnley.  Palmer shared this house with a lodger, Kieron Davison.

 

Alan Palmer then left a voicemail message on Peter Leonard's mobile phone, stating that Alan Street was at his house and inviting Leonard to call back urgently. 

 

A forensic analysis of Leonard's and Alan Palmer's phone records reveals that there were a number of conversations between them in the early hours of 20th December 2008.

 

Street and Leonard used to be friends until Street began dating Leonard's ex-girlfriend.  They fought and Street knocked Leonard unconscious.  This led to an irrevocable breakdown of their friendship. 

 

Alan Palmer's phone call to Leonard was clearly offering him the chance to take his revenge on Street.
 

Violence 'beyond belief'
 

Whilst at Alan Palmer's house, Street became the victim of a sustained and prolonged attack. 

 

He was punched and kicked and struck with both a wooden pole and a litre size whisky bottle.  He was stabbed in the eye, ear and back of the head with a pair of scissors.  A plastic bag was placed over his head.

Evidence of Murder

 

The police did not become aware that a murder had been committed until 21st December 2008, when they received an anonymous phone call.  The caller stated that there was a lot of blood and a sack of bloodstained clothing at a house in Stockbridge Road, Padiham.

 

When police searched the address given by the caller they found nothing.  The call was either a hoax or the caller had made a mistake with the house number. 

However, while the police were searching the area, they discovered a smashed front window in another house in the street (number 29).

 

A preliminary search of this house revealed a black sack containing bloodstained clothing and a wooden pole. 

 

A forensic team was called to make a full search of the house, and they found massive amounts of blood downstairs.  It was obvious that a sustained and violent attack had taken place.

Much of the blood was difficult to see with the naked eye because the carpet and sofa were both a deep shade of red. 

Unlike TV police and forensics programmes, the scenes of crime officers did not spray luminol everywhere to determine the presence of blood.  Instead, they used high intensity light sources, which visualised the blood spatter patterns without damaging them in any way.

(Luminol should, really, only be used as a last resort.  Luminol is water-based and can cause smearing of bloodstains or further dilute an already diluted bloodstain.  Luminol may also cause the loss of genetic markers, which restricts DNA profiling).

Police enquiries revealed that Alan Palmer and Kieron Davison lived at 29 Stockbridge Road.

While the police were searching outside the house, Mark Palmer arrived.  The police told him only that they were responding to a call about the broken window. 

Mark Palmer then attempted to call his brother to tell him about the broken window, but was unable to get in touch with him.  Kieron Davison had also not returned home.

Kieron Davison and friends

Over the next few days, friends of Davison rang the Burnley Major Incident Room with information 'about the murder'.

It was not long afterwards that police received a tip-off about Davison's whereabouts and succeeded in arresting him.

Davison had been taking his friends round to the house to view the aftermath of the murder. 

He told police that when he arrived home in the early hours of 20th December 2008, 'somebody' was there, who was being attacked because he was a paedophile.  Davison admitted to punching this 'somebody'.

The police never believed Street was a paedophile, although he was a convicted rapist (of an adult).

Davison told police that the 'paedophile' had been put in the boot of a car, a blue Mitsubishi Colt.

Piecing it all together

In the meantime, the blood in the house was identified by DNA analysis as belonging to Alan Street.

                                                

 

                                                                    Alan Street

The police then began the painstaking task of tracking his movements on the night of 19th December/early morning 20th December 2008 by viewing CCTV footage of Burnley town centre.

The CCTV footage coupled with the phone records of Alan Palmer led police to Peter Leonard, who, they considered, had the most likely reason to want to attack Street i.e. their fight over Leonard's ex-girlfriend.

On the CCTV footage at the beginning of this blog, Peter Leonard has stopped at a petrol station to buy cigarettes and is on his way to Stockbridge Road by taxi.

But Alan Palmer and Leonard had apparently disappeared.

The blue Mitsubishi Colt was proving to be equally elusive.  It took ten days for the police to
locate the vehicle.  It had been parked in a residential street in Accrington, three miles away from Padiham.

There was no body in the boot, but there were traces of blood, which were identified as belonging to Street.

Street's body was eventually discovered by Environment Agency contractors on 19th January 2009, lying face down in knee-high water in a culvert in Accrington.

The post-mortem examination suggested that he may have survived for half an hour to two hours after the attack.

Alan Palmer and Peter Leonard eventually handed themselves in to police and were tried and convicted of murder.

The investigating officer, Detective Inspector Neil Hunter said 'The level of violence used in this sustained and prolonged attack was beyond belief'.




 

 

 

 

 

 

 

 

 

Hungry Burglars Beware! Fingerprints Can Be Developed On Food

A number of burglars are unable to resist the temptation to snack on a piece of fruit or chocolate whilst relieving the householders of their more valuable worldly goods. 

 

But rather than taking their apple cores home or eating a whole chocolate bar, many burglars will discard the remains of their snack at the scene  - and leave behind valuable forensic evidence in the form of teeth marks.
 

In Adelaide, a burglary took place in an up-market chocolate factory.  The burglar sampled a few of the products but left the half-eaten bars at the scene.  A forensic odontologist was able to match the teeth marks in the partially-eaten chocolate bars with dental impressions taken from a suspect. 

A quick online search will find many other, similar, examples.

 

In general, food is overlooked as a source of forensic evidence.  However, a perpetrator may handle a piece of food at a crime scene, even if he/she does not eat it.  Consequently, the potential exists for an apple or an orange, for example, to yield fingerprint evidence. 

An item of food may have a porous or non-porous surface, which may be smooth or rough, but it is unlikely to be completely uniform across its surface.  This makes it difficult to choose the best technique for developing fingerprints.

Some techniques are designed specifically to recover fingerprints from porous surfaces, whereas others are designed for non-porous surfaces.  Using the wrong technique may damage the fingerprint and the evidence will be lost.

Until recently, fingerprints had only been recovered from food by scientists from Slovenia and India.  Scientists in the UK were, naturally, interested in these results.  However, the chemicals that were used in the Indian and Slovenian studies are not used to recover fingerprints in the UK.

Scientists at Abertay University in Scotland set out to discover whether they, too, could recover fingerprint evidence from food, but without using the chemicals in the Indian and Slovenian studies.

They started out using conventional UK chemical techniques, but, as expected, the results were disappointing. 

They then turned to Powder Suspension, a thick, tar-like substance that is used to recover fingerprints from the sticky side of adhesive tape.

Here is a video showing how fingerprints can be developed on the sticky sides of duct tape, masking tape and electrical tape.

By modifying the consistency of Powder Suspension and making it more dilute, the Abertay researchers obtained identifiable prints on smooth-skinned fruit and vegetables, including bananas, apples and onions. 

The technique was less successful on potatoes, which are rough-skinned, and eggs, which are porous.

Much more research will need to be carried out before this technique can be used operationally on food at crime scenes.  But, it should give potential burglars something to ponder.  Food for thought, you might say............

Do leave a link to your book/story in the Comments section.  I'd love to read your work.



 

Super-speedy DNA extraction technique is perfect for crime drama

In a single episode of CSI, the featured crimes are solved to everybody's satisfaction and all loose ends are nearly tied.  Those of us with forensic knowledge will probably think 'Yeah, right', but are willing to suspend our disbelief.  It is entertainment, after all.

 

Now, however, solving a crime in an hour may not be so far-fetched after all.

 

 

 

Image courtesy of www.all-about-forensic-science.com

 

 



Engineers at the University of Washington, in collaboration with a company called NanoFacture, have created a device that can extract DNA from body fluids in a matter of minutes.

 

DNA extraction is a complex process, which can take 20 - 30 minutes to complete.  It also requires toxic chemicals, so it is not environmentally friendly.

 

This new extraction technique uses microscopic probes.  First of all, the probes are dipped in the body fluid.  Then an electric field is applied within the fluid.  This causes the DNA molecules to stick to the probes. 

The DNA molecules therefore become trapped on the probe surface.

 

This whole process from body fluid to pure DNA takes only 2-3 minutes.

 

Once the DNA has been extracted, a profile can be generated in the usual way.

 

Here is a link to an article which describes the technique in more detail.

 

New Device Can Extract DNA In Minutes

 

Although the article is slanted more towards medical application of the technique, its potential value in forensic investigations is acknowledged.

 

Here is a (very) short video showing the equipment in use.

 

 

Given that many forensic laboratories have huge DNA analysis backlogs, the time savings on the extraction process could make a considerable difference to throughput.

 

From a crime writer's point of view, this technique offers another way to inject realism into your plotting, but without the need to compromise on reality (unless you want to, of course). 

 

Which forensics techniques do you use in your writing?  Why not let me know in the comments section below; don't forget to include a link to your book or story.

Using Forensic Entomology to establish Post-Mortem Interval

Forensic entomology is 'the use of insects and their arthropod relatives to aid legal investigations'. (Arthropods belong to a group of animals that includes spiders, crabs, scorpions and centipedes, as well as insects).

Forensic entomologists are usually attached to a college or university department, although some will be employed at a museum of natural history.  A forensic entomologist's caseload would not usually justify a position in a forensics laboratory.  Forensic entomology is mainly a sideline to the teaching and research duties of their regular job.

 

There are three major branches of forensic entomology.

 

1. Medico-Legal (Medico-Criminal) Entomology

 

This branch is concerned with the investigation of mainly criminal cases, particularly homicide.  The bulk of the work of the forensic entomologist will involve determining the Post-Mortem Interval (sometimes called 'elapsed time since death') or site of death.  The Post-Mortem Interval is the time between death and the discovery of the body.

Other cases may involve the criminal use of insects, such as when a parent deliberately stings their child with a wasp or bee as a form of punishment.

In cases of unexplained death, where the corpse is too decomposed for the analysis of stomach contents, urine or blood, it is possible to analyse maggots, empty puparia (cases that contained the pupae) or larval skin casts in or on the corpse for evidence of poison.

When investigators need to know the route taken by a car - and there is no GPS navigation device in use or CCTV evidence - a forensic entomologist may be called in to examine the fragmented remains of insects that have become splatted against the windscreen, front fascia and radiator of the vehicle.  Identification of the insect species can provide evidence of the probable passage of the car through a particular area.

2. Urban Entomology

This branch deals with the insects that affect both man and his immediate environment.  The legal proceedings may be heard in either the criminal or civil courts, depending on the case e.g. monetary damages cases will be civil proceedings.

Examples include problems with cockroaches, termites and other pests, insect nuisance from agriculture and neglect cases involving insect infestation of patients in hospitals and care homes.     

3. Stored Product Entomology

This branch is mainly concerned with civil disputes involving insects and other arthropods in food and stored products, but can also include criminal investigations.. 

Different species of arthropods may often be found together in stored containers of illegal drugs.  The drugs are most likely to have been manufactured in one country and sold in others.  If a forensic entomologist identifies the arthropods and then plots their world distribution on a map, any areas of overlap between the species can indicate, approximately, where the drugs might have come from.

Further study of the biology of the identified arthropods may provide information on the surroundings in which the drugs were produced or packed.

Stored Product Entomology also covers cases of fraud where insects have been deliberately introduced into packets of food with the aim of claiming substantial 'compensation'.       

Whilst there are a lot of fascinating cases involving insect evidence - which I can come back to in other blogs - I want to concentrate on the use of forensic entomology to establish the Post-Mortem Interval (PMI), since this is the major area of a forensic entomologist's expertise.

The lure of a decaying corpse

As far as an insect is concerned, a human corpse is a piece of carrion which provides the perfect medium for feeding and reproduction.  Although a wide variety of insects will be attracted to the decaying remains, flies are the most important group from a forensic entomologist's viewpoint.

A forensic entomologist will not need to be called in to assist an investigation until the body is 72 hours or more old.  Up until this point, other forensic methods are either equally or more accurate than insect evidence.  However, after this time, insect evidence may be the only method of determining the PMI.

How to determine the Post-Mortem Interval

There are two methods of determining the PMI.

1) Using Successional Waves of Insects

This method is used when the corpse has been dead between a month and up to a year or more.

During decomposition, the remains go through a variety of biological, chemical and physical changes.  Different stages of the decomposition are attractive to different species of insects.

The first insects to arrive are the blowflies.  They can arrive within 24 hours of death if the season is suitable. 

Other species are not interested in the fresh corpse.  Cheese skippers, a worldwide pest of cheese and bacon, will arrive between 3 - 6 months after death, during protein fermentation.  Beetles that feed on bones will not arrive until the bone is exposed.

Some insects are not attracted to the body itself, but feed on the insects already present.

Ultimately. there will be many species involved at each stage of decomposition.  Each group of insects will overlap with those arriving immediately before and after. 

The forensic entomologist will therefore analyse the groups of insects that are associated with the corpse.  He or she will also need knowledge of the local insect population, as well as knowledge of insect succession and the times of carrion decomposition.

Having all this information in place will allow the forensic entomologist to determine a window of time in which death took place.

2) Using Maggot Age and Development

This method can allegedly give a date of death accurate to a day or less, but more likely a range of days.  It is used in the first few weeks after death.

The theory behind estimating PMI is simple.  Since insects arrive on the body soon after death, by estimating the age of the insects on the corpse, it is possible to estimate the time interval since death.

Maggots are the immature stages of the Diptera or two-winged flies.  The maggots of forensic interest are those of the Blowfly, the first insects to arrive on the dead body.

Here is a  slightly grisly video, explaining the importance of blowfly maggots when estimating the PMI.

As mentioned in the video, each of the developmental stages in the blowfly's life cycle takes a known time.  This is dependent on temperature and available food (not usually a limitation where a corpse is concerned).  Development takes longer in cooler temperatures.

Here is the basic procedure from call-out to a corpse to estimation of the PMI.

1) Collecting, preserving and packing specimens

Samples of insects at all stages of their life cycles are collected from the body, but the maggots are the most important.  Wounds and natural orifices are particularly good collection areas.  Insects should also be collected from clothing, coverings and the surrounding soil, for example.

Some samples should be preserved in 75% alcohol; the remainder should be kept alive for growing on in the laboratory.  Preserving the maggots, etc. allows the entomologist to keep an accurate record of the stage that they were at when they were collected.

Here is a video showing the type of equipment used at crime scenes to collect insects.

The samples are packed in cardboard boxes with a good air supply and taken to the entomology laboratory.

In addition to collecting samples, the forensic entomologist must make extensive notes about the habitat of the death site, take the temperature and humidity at the time of collection and assess the weather conditions.  The elevation and map coordinates of the death site must also be noted.

He or she must also make detailed records about the corpse, such as whether or not clothing was present, was the body buried or covered, depth of burial or covering, location and type of wounds, state of decomposition, how many maggots are present (if any) and whether the body been moved to this site after death.

2) At the entomology laboratory

When the live maggot samples arrive, they will be measured and examined and then placed in a jar with some food, such as beef liver.  The food is placed on top of some sawdust; the maggots will burrow in the sawdust to pupate.

When they pupate, they are taken out of the sawdust and placed on damp filter paper in a petri dish.

The forensic entomologist notes down when pupation occurs and how long it takes.

When the adult emerges it is killed and pinned and placed in an insect box.  The same fate happens to any adult flies collected directly from the corpse.

It is only when the collected eggs or maggots have developed into adults that the forensic entomologist can be absolutely sure which species have/has colonized the corpse.

3) Estimation of PMI

The estimation of PMI is based upon direct age assessment of the oldest specimens developed on the body. 

By relating maggot development to local climatological data from the period prior to the discovery of the corpse, the forensic entomologist can estimate the number of days that it would take for the maggots to reach the size and stage found on the remains.

This time period is the PMI.

Here is a video showing more maggots and pigs carcasses, but it has some good time-lapse photography.

I'll leave you with a video showing 'celebrity' forensic entomologist, Dr Lee Goff, talking about his work. 

Forensic entomology is a huge subject and this blog has only scratched the surface.  I plan to re-visit the subject soon.

Don't forget to leave a comment and a link to your book.