How Familial DNA Searching Could Aid Cold Case Investigations

On 23rd March 1988, Debbie Linsley said goodbye to her parents and drove to Petts Wood railway station with her brother, Gordon. 

Debbie, 26, worked in Edinburgh but had been attending a management course in London. Her parents lived only 15 miles or so from London, so it was a good chance to have a family get-together, particularly as Debbie was going to be a bridesmaid at her brother's wedding in two weeks time.

Gordon dropped off Debbie at the station and she caught the 14.16 Orpington to London Victoria train. 

In those days, many of the train carriages had no corridors.  Instead, they were divided into compartments.  Within each compartment, the seats faced each other along its width and there was a slam door on either side. 

If you were travelling on your own at a quiet time of the day, you ran the risk of being in dubious company at some point in your journey.

Some six minutes away from London Victoria station, Debbie's train stopped at Brixton to pick up passengers.  In that final six minutes between Brixton and London Victoria, Debbie was stabbed eleven times in a frenzied attack.  She put up strong resistance and managed to injure her attacker.  However, she died from a stab wound to the heart.

Debbie's body wasn't discovered until ten minutes after the train arrived at London Victoria.  Her attacker was long gone.  At that time, there was no CCTV to record the passengers leaving the train. 

The police investigation was thorough but the murderer has never been caught.  The murder weapon has also never been recovered. 

But the killer did leave a small sample of his blood at the scene.  Although DNA profiling was not in use in 1988, the case has been subject to periodic reviews.  As a result, the new investigations have taken full advantage of the latest techniques in DNA profiling.  Finally, the scientists were able to generate a full DNA profile of the crime scene blood.

But the killer's DNA profile isn't on the National DNA Database.

Investigators are convinced that Debbie did not know her killer.  They also discount the 'known killer' theory.  This is because a person like Debbie's killer would surely have committed other crimes.  If so, he would more than likely have been arrested for some of them and had a mouth swab taken for DNA profiling. 

Maybe the killer is dead.

But 25 years after Debbie's murder, another cold case review is taking place.  This time the investigators propose using Familial DNA Searching.  Instead of searching the National DNA Database for a profile that matches the crime scene profile, scientists will search for relatives of the offender who may be on the Database.   

One argument for its use is that criminality tends to run in families.  Another argument is that it is a way of keeping the investigation going.

Familial DNA Searching was developed in 2002 by the Forensic Science Service in England.  It is based on the principle that close genetic relatives such as a parent and child or siblings wll have more DNA in common than unrelated persons. 

When a search is made and a number of possible relatives have been identified, further profiling techniques are used to verify or exclude the possibility of relationship with the unidentified offender.

The use  of Familial DNA Searching is controversial, particularly in the United States.  Although openly carried out in California and Colorado, familial searching is banned in Maryland.  Critics describe it as an invasion of privacy or a 'genetic fishing expedition'. 

However, the technique proved effective in identifying a serial killer suspect in California known as the 'Grim Sleeper'.

This is how ABC reported the news of the Grim Sleeper suspect's arrest.

Finally, here is an excellent article detailing successful cases where familial DNA searching has been used, more about the technique itself and the arguments for and against the technique.

Familial Seaching: Extending the Investigative Potential of DNA Typing

Let's hope familial DNA searching proves its worth in the Debbie Linsley case. 









 



What's the Difference between Entrance and Exit Gunshot Wounds?

Firearms account for almost two-thirds of homicides in the United States, so unsurprisingly, gun crime is a popular subject for modern crime fiction. 

 

Ballistics and the forensic examination of firearms are complex topics.  When the crime writer Ruth Rendell was at the height of her popularity, she said she no longer wrote about guns in her novels because she always got something wrong. 

 

I'm sure many crime writers feel the same.  So let's turn the subject on its head and start with the results of firing a gun at somebody.  (We'll look at the forensic aspects of the firearms themselves in future blogs).

 

Gunshot wounds can provide a lot of information about what happened in a shooting, such as the make and model of gun, the range of fire, the sequence of fire patterns, the path travelled between entrance and exit wounds, the likelihood of survival and the specific manner of death.

 

What are the basic features of gunshot wounds?

 

Entrance Wounds

 

• Appear as a punched-out hole in the skin.

• Diameter of the wound is usually smaller than the bullet.  This is because the skin is elastic and it retracts after the bullet enters the skin.

• There is an abrasion ring (sometimes called the abrasion collar) around the wound.  This is a ring of skin with the outer layer or epidermis missing, through which small amounts of blood can escape.

• Underlying tissues will not protrude.

• Tattooing or smudging (gunshot residues) may be present around the wound depending on the distance of the shooter from the victim..

Exit Wounds

 

• Exit wounds from low velocity fireams tend to be relatively small.  They can have a variety of shapes e.g. slit-like, X-shaped, irregular.

• Exit wounds from high velocity firearms tend to be large and destructive. 

• A typical exit wound does not have an abrasion ring.

• Underlying tissues may be protruding.

• Tattooing or smudging is always absent.

Of course, the bullet may not actually exit the body, particularly if the ammunition is low calibre.

A more detailed account of the features of entrance and exit wounds, where the entrance wounds are characterised according to the distance from which the shot was fired, can be found here.

Another difference between entrance and exit wounds concerns bloodspatter.

 

Backspatter is ejected from entrance wounds and travels against the line of fire towards the person firing the gun.  If the shooter and gun are close enough to the victim, this blood may be deposited on the shooter's hands or the firearm itself.  Clearly, there is the potential for good associative evidence here.

 

By contrast, forward spatter is ejected from the exit wound and travels in the same direction as the bullet.

If you are a regular reader of my blog, you'll know that I  wuld normally include a video here, to illustrate what I have been writing about.  However, I couldn't find anything appropriate, so instead here is a gunshot wounds presentation from the Health Training Network.   Although the photographs may be upsetting for some of you, the quality of the information is excellent.  I hope you can find something from it to use in your writing.

I'll come back to this subject in future blogs, but do leave a question if there is something that you particularly want to know about gunshot wounds or firearms forensics and I'll try and help you.

I'd love to know how your writing projects are proceeding.  How close are you to publication?  Maybe you're already a published author.  Why not leave a comment at the end of this blog with a link to your latest book?  

Forensic Botany - an under-used source of potential evidence

Forensic Botany is the application of plant science to the investigation of criminal and civil cases.  The value of using plant remains as evidence lies in the fact that they can be found almost everywhere.

 

But despite its proven value, forensic botany is not part of mainstream forensics.  Its practitioners tend to work in university departments rather than forensics laboratories.

 

A major obstacle to the routine use of botanical evidence has been the lack of trained specialists. 

 

As a degree subject, botany began to wane in popularity in the 1970s. (There were only six of us majoring in botany at my university in 1974).  The courses were viewed as old-fashioned, with their traditional content of plant morphology, anatomy, and systematics.  Instead, students flocked to those courses offering the study of plants at the molecular level.

 

Today, forensic botany encompasses expertise in both traditional plant science and molecular biology.  As well as the interpretation of botanical evidence left at a crime scene, forensic botanists are able to identify individual plants from an analysis of their DNA.

 

So how can forensic botany help an investigation?  Here are a few examples.  The list is not exhaustive, as I am planning on re-visiting this subject in future blogs.

 

• Seeds can be carried in trousers turn-ups (cuffs), thereby potentially linking an individual wth a specific location.

• The identification of vegetable matter in stomach contents can provide evidence of a victim's last meal.

• Pollen types that occur together in a crime scene sample can show where somebody or something has been.  This can be very specific evidence.  It can indicate geographical origin in instances where certain plants only occur in particular areas in certain combinations.


• From the use of plant growth patterns and habitat details, it is possible to infer how long skeletal remains have been present in a particular location.
 
• DNA analysis of fragments of marijuana can establish distribution patterns and links between growers.

Here is a short video that shows how forensic botany can be used to determine that a body has been moved.  The video also shows how a perpetrator can be linked to a scene or victim by plant material.

 

Forensic botany is an important tool for the location of clandestine graves.  Here is an account of a double homicide where pollen evidence helped police find the graves of the victims.

 

On 6th December 1994, Roger Severs was found guilty of the murder of his parents, Derek and Eileen Severs.  He was sentenced to two terms of life imprisonment.

 

Roger Severs was unemployed and lived with his parents at their home in Hambleton, Leicestershire, UK.  One evening, Severs returned home drunk.  His mother was at home, alone.  Severs asked her for money, probably to fund his latest business idea.  When she refused, he flew into a rage and battered her to death with a steak mallet.

 

Later on, when his father came home, Severs beat him to death as well.

 

Derek and Eileen Severs were comfortably off and Roger Severs could expect a good inheritance.  They had been actively involved in their local community and had many friends.  After a week of missed appointments - which was totally out of character - and despite being told by Severs that his parents were on holiday, their friends became increasingly worried and called the police.

 

When the police arrived at the couple's bungalow, they found it in a state of disarray.  In particular, they noticed that the carpets had been removed from two of the rooms.  Severs was adamant that his parents were on holday.

 

However, the police investigations revealed Derek and Eileen had not made any travel arrangements.  Instead, it was clear that they had no intention of going on holiday, as they had made a number of appointments to see friends when they were supposedly away.

 

Two days later, the police arrested Severs and a forensic examination of his parents' bungalow was carried out.

 

Scenes of Crime Officers (SOCOs) found blood spatter in the bathroom, indicating that a violent attack had taken place.  Blood traces near the garage were indicative of a second attack. 

 

The SOCOs also found a trail of yellow fibres with a 'rolled' appearance, suggesting that something heavy had been dragged over the carpet.

 

But where were the bodies? 

 

It was possible that they had been taken to another location.  Derek and Eileen's car was extremely muddy, both inside and out.  The SOCOs took mud samples from the wheel arches and footwells of the car.

 

A detailed analysis of the mud showed that it had been accumulated recently and contained quartz, calcite, ironstone, chert and coated road stone.  A forensic geologist concluded that this mineral composition indicated that the mud had come from an unmade road (trail) in East Leicestershire.

 

A further analysis of the mud revealed several types of pollen grains, in particular, oak, birch and horse chestnut.  The density of the oak pollen suggested that the car had been taken to a site next to an oak tree and also showed the direction in which it had been parked.

 

In order to locate the likely grave site of Derek and Eileen, Professor Tony Brown of Leicester University, a forensic botanist specialising in palynology (pollen analysis), collaborated with ecologists from the Leicestershire and Rutland Wildlife Trust, who possessed good knowledge of the tree species in the surrounding countryside.  Between them, they reduced the search area from a 40km radius to five likely woodlands.  Derek and Eileen's bodies were discovered at the second site that was searched.

Eileen was wrapped in a yellow blanket, hence the trail of yellow fibres found by the SOCOs. 

The soil on top of the bodies came from Derek and Eileen's garden.  Severs had first of all placed the bodies in a shallow dip.  He then drove to and from their bungalow with bags of soil. He emptied the bags on top of the bodies and disguised the grave with leaves and twigs.

The SOCOs found a 'To do' list which Severs had written after the murders.  One of the tasks was to clean the car. Fortunately, he was arrested before he had completed that particular chore.

 

There are lots of interesting cases where plant evidence is important, so, as I mentioned earlier, I'll re-visit this subject in other blogs.  In the meantime, I hope this blog has 'planted' some new ideas that you can use in your writing. 

 

Please feel free to share this article on Google+.  You can also follow me on Twitter @forensicswrite

 

 

 

 

 

 

 

 



Can 'Robocop' improve Accuracy of Eyewitness Testimony?

Erroneous eyewitness testimony accounts for more wrongful convictions than any other cause.  Juries love eyewitnesses; after all, what could be better than the testimony of the person who actually witnessed the crime taking place?  Well, solid forensic evidence, for one thing.

 

Numerous studies have been carried out which demonstrate that eyewitness testimony is unreliable.  It can be particularly inaccurate when the eyewitness is 'identifying' a person of a different race from themeselves. 

Here is a video showing just how wrong eyewitnesses can be.

 

 

 

Were you a better eyewitness than these students?  I was okay on the clothes but poor on the facial details.

So can anything be done to make eyewitness testimony more reliable?  Maybe.

 

Forensic psychologists have been researching eyewitness memory and eyewitness testimony for decades.  There are three stages of eyewitness memory: 

1. Witnessing the incident
2. Waiting to provide testimony about the incident
3. Providing testimony about the incident

You can read about the three stages in more detail here. This is a good website (although the design is a bit messy), where you'll find a variety of useful resources.

As you would expect, the length of time between the incident taking place and providing testimony about it affects the ability of the witness to recall the events accurately.  Furthermore, the language used to question the witness can also influence their testimony.

 

What if a robot asked the eyewitness questions about the incident instead of a human interrogator?  Researchers at Mississippi State University have carried out experiments using both robot and human interrogators.  As part of the study, the robots and humans introduced false information into their questioning.  They all asked identical questions, using the same script.  Only the human interrogators elicited erroneous information from the witnesses.

Here is a link to an article about this research.

 

 http://www.newscientist.com/article/mg21729036.100-robot-inquisition-keeps-witnesses-on-the-right-track.html

I'm sure it will be quite some time before 'Robocop' is routinely questioning eyewitnesses but it is an interesting proposition.  Any improvement on the current system has to be welcomed.  It's not working well at the moment.

Please share my article on Google+.  Don't forget you can follow me on Twitter. https://twitter.com/forensicswrite


 

Images of Death; the Virtual Autopsy

When a person dies in suspicious circumstances, a forensic pathologist will be called on to perform an autopsy on the deceased.  The purpose of the forensic autopsy is to determine:

• the cause of death e.g. blunt force trauma, gunshot, etc., 
 
• the mechanism of death i.e. what was actually used to bring about death e.g. baseball bat, gun etc.,
 
• the manner of death e.g. homicide.

 

The forensic autopsy may also provide valuable evidence on the size, shape and features of the murder weapon, as well as give an indication of the time of death.  However, a  forensic autopsy cannot discover why the victim died. 

 

Police officers may rely heavily on the autopsy findings in the early days of a criminal enquiry to determine the direction of their investigations.

 

However, sometimes, the body may be so decomposed that the pathologist cannot give any sort of opinion as to the cause of death.  Furthermore, the act of cutting into a badly decomposed body can create further damage, leaving the pathologist with even less to examine.

 

Fortunately, there is now an alternative method of obtaining evidence from decomposed and badly damaged bodies, which is gradually being adopted around the world.  It is also used on 'fresh' bodies. 

 

The Virtual Autopsy or 'Virtopsy' is the brainchild of Michael Thali and his team from the University of Bern, Switzerland.  The initial research project arose from a need to solve a high-profile homicide.  A possible murder weapon had to be compared with the impression in the skull of the victim with a view to identifying the weapon with a high level of certainty.  The Virtopsy developed from this research.  

Essentially, the Virtopsy uses modern, cross-sectional imaging techniques to supplement and partially replace traditional autopsy.  The results of the Virtopsy are presented as a permanent 3-D digital record.  You may be familiar with two of the processes used in the Virtopsy process from hospital visits, namely CT and MRI.

 

Computed Tomography or CT is an imaging method that uses X-rays to create pictures of cross-sections of the body.  A computer creates separate images of the body, which are called 'slices'.  In a Virtopsy, CT scans can be used to detect air embolisms and the effects of decomposition, for example.

 

The magnetic resonance imaging (MRI) technique uses magnetic and radio waves to create high quality images of tissues and organs within the body.  It is used to detect soft tissue injury and organ trauma, for example.

 

In addition, angiography may be used to address any circulatory questions.  Here,.a liquid dye is injected into the body to make the blood vessels easy to visualise.

A robotic system called a 'Virtobot' can be used in conjunction with the CT scanner to sample tissues from the body as well as documenting (recording details of) the surface of the body at high resolution.

To see how all this fits together, here is a Virtopsy video showing the 'workflow' of the process.  Here you will see all the equipment demonstrated, mainly on a dummy.

 

 

 

 

 I've also found this useful chart that lists the processes involved.

There are many advantages of a Virtopsy over a traditional forensic autopsy.  Here are a few:
 

• The technique is non-destructive.
 
• A permanent and easily retrievable digital record is available to allow consultation with other colleagues or when a second autopsy by another pathologist is requested by the opposing legal team. 
 
• A permanent 3-D image of the findings of the Virtopsy allows every pathologist to examine the same material, no matter how far advanced the investigation.
 
• The body is effectively preserved in digital form, so there is no need for an exhumation if new evdence comes to light in the future.  Also, no evidence has been lost if the body has been cremated.
 
• Trauma that would be impossible to see in a traditional autopsy may be detected by a Virtopsy.
 
• 2-D and 3-D post-processing of the Virtopsy images helps the pathologist to visualise the findings for presenting evidence in court.
 
• It is easy to examine bodies that are contaminated by infection, toxic substances or biohazards.
 
• The Virtopsy overcomes any religious or moral objections to autopsy. 

Here is a video showing the Virtopsy in casework in France.

 

 

 

Could the Virtopsy ever be a replacement for the traditional forensic autopsy?  At the moment, I suspect the answer is no.  It's primary use is as a tool to be used in cases where dissection is not feasible, such as a badly decomposed body, or where the forensic evidence is particularly hard to visualise, such as matching a weapon to an impression on the body.

 

I hope you found this blog post useful.  I welcome your comments. Please let me know if there is anything particular you would like me to write about.  I'll be glad to oblige.

 



DNA confirms skeleton as Richard III

Back in November, I wrote a  blog post about the scientific tests being carried out on a skeleton, which was found by a team of archaeologists while excavating the site of Grey Friars friary in Leicester.  Grey Friars was known to be the burial place of Richard III.  Could the skeleton actually be the remains of the English king? 

 

As soon as the skeleton was discovered, the bones were excavated under forensic conditions and a battery of tests was carried out to try and answer this question.

 

Last week, the results of the tests were made public.  They showed 'beyond reasonable doubt' that the skeleton was that of Richard III.  The clinching piece of evidence was the DNA match between the mitochondrial DNA (mt-DNA) of the descendants of the family of Richard III and the skeletal remains.  Fortunately, there was no degradation of the mt-DNA in the bones, so the scientists were able to obtain a useful profile.

 

So how does the evidence stack up?

 

• Radiocarbon dating revealed the date of death as being in the second half of the 15th century or the early 16th century.  Richard III died in 1485.

• Radiocarbon dating also revealed that the individual ate a high protein diet in life, which indicates a person of high status and wealth.

• The cause of death  was from one of two fatal injuries to the skull.  Altogether, ten wounds were discovered on the skeleton.  Richard III was killed at the Battle of Bosworth.
• The skeleton revealed scoliosis (curvature of the spine).  Although 1.7m (5ft 8ins) tall, the individual would have stood significantly shorter and his right shoulder may have have been higher than his left.  Shakespeare portrays Richard III in this manner.
• The mt-DNA matches two of Richard III's maternal line relatives.  The family relationship has been verified by a genealogist.

Here is a link to the Unversity of Leicester website which has videos of the excavation, some of the tests and the press conference announcing the results.

 

The Search for Richard III

 

This was, clearly, exciting news for forensic science and history.  It was also very lucky that a DNA analysis was possible i.e. a profile could be obtained from the bones and a source of DNA was available from verifiable descendants.

 

Needless to say, the British press went into overdrive immediately after the results were announced.  However, I do want to share one particularly interesting article with you. It reveals how a team of scientists from Dundee University in Scotland went about the task of recreating the face of Richard III - without going anywhere near the skeleton.

The face of Richard III

 

I hope you enjoyed this blog post.  Please feel free to share it with your friends.  Do let me know if there are particular topics you would like me to blog about.  Perhaps I'll give bones a rest for a little while! 

 
 
 

 

 



Bones of Contention

Traditionally, forensic anthropologists determine the biological sex of adult or adolescent skeletal remains by evaluating the size and shape of the pelvis.  If the pelvis is missing, features of the skull, such as the browridge and mandible, can be used instead.  Measuring the long bones e.g. the humerus is a much less accurate method for sex determination, but sometimes, this is as good as it gets

How a forensic anthropologist goes about solving the problem of sex determination is demonstrated in this video, produced by the National Forensic Science Technology Center.  It shows a seminar entitled 'The Determination of Biological Sex from the Human Skeleton'.  It isn't too technical and has plenty of visual aids.  It's just over 20 minutes long but it is a very good overview of the subject.

In the seminar, the accuracy rate for determining biological sex using a visual examination of the pelvis is given as 90-95%.  In 2010, researchers at North Carolina State University published a method of determining biological sex using 3-D imaging technology of the pelvis.  They claim a 98% accuracy rate, or better, using their technique.

An added benefit of the NCSU technique is the ability to determine biological sex from pelvic fragments.  The examination of fragments can be a major stumbling block with traditional methods.  Unless the sex determination indicators are present in the fragment, the examination may come to nothing.  The researchers from NCSU hope to have solved this problem. 

The researchers chose 20 'anatomical landmarks' which differentiate males from females on the os coxa or hip bone.  They measured these 'landmarks' using 3-D imaging technology.

So, to determine the sex of a skeleton from a fragment of pelvic bone, the forensic anthropologist uses a digitiser to create a 3-D map of the fragment and measures the relevant anatomical landmarks.  These measurements are then compared with the published measurements for the same landmarks to determine the sex.      

This type of quantifiable data holds up well in court.  Rather than the forensic anthropologist having to present an expert opinion, which can sometimes be difficult for juries to comprehend, he or she can present a set of figures.  This is tangible and should be more meaningful to a jury.

Here is a link to an article about the research:

New technique for determining the sex of skeletal remains

Last week, researchers from the University of Granada in Spain published details of a new imaging technique for identifying the age and sex of skeletal remains, using features of the pubis.  The pubis is one of the three bones of the os coxa (hip bone).  In adults and adolescents, the three bones are fused together.

Traditionally, forensic anthropologists have considered that the pubis was only useful for the identification of remains in the age range 20-40.  However, the researchers found that they obtained good results from bodies of people older than 50, particularly men.

This new method of age and sex determination essentially combines imaging techniques with statistical analysis.  It is reckoned to be state-of-the-art and user-friendly, with an accuracy rate of 95%.

You can read about it here:

New imaging technique for identifying the sex and age of a corpse

I hope you have found something in this blog that you can use in your writing.  Do let me know if there are any topics you would particularly like to know more about.  I'm also happy to answer your forensics questions.  Don't forget to follow me on Twitter @forensicswrite.