Gut Feeling

This is my last blog of 2012, and as it is the festive season, I'm going to write about intestinal micro-organisms!

 

We humans live with a large population of micro-organisms in our intestines.  Collectively known as gut flora, they perform a variety of useful functions, such as extracting nutrients from food, training the immune system to respond only to pathogens and preventing the growth of harmful bacteria.

Now, researchers at Washington School of Medicine in St Louis and the European Molecular Biology Laboratory in Heidelberg, Germany, are suggesting that our gut flora may have an important part to play in forensics.  Just as our DNA varies from person to person, so, apparently, does the DNA of the micro-organisms in our intestines.  This means that a person may be identifiable from the DNA profile of their gut flora.

Here is an account of the research:

New Genetic Fingerprint lives in your Gut

Clearly, the overall purpose of the research is to improve human health.  But advances in forensics often come from unexpected sources.  The revolutionary approach to developing invisible indented impressions of writing on paper arose, almost accidentally, from research into latent fingerprint development techniques.

So, if one of your characters leaves a series of anonymous letters smeared in excrement in a number of other characters' mailboxes (it does happen), maybe this new technique could provide a starting point for the police investigation.  Just a thought.........

If you celebrate Christmas, have a wonderful time and don't treat your gut flora too badly!  Thank you for reading my blog this year, and  I hope to connect with you again in 2013.

Don't forget to follow me on Twitter @forensicswrite.



The Sole Evidence

On 27th July 2008, at approximately 5am, newlyweds Ben and Catherine Mullany were shot and robbed in their hotel bedroom on the last day of their Antiguan honeymoon.  Catherine died instantly; Ben went into a coma and survived long enough to be flown home to Wales, but doctors could do nothing for him.  A week later, his life support machine was turned off. 

Two weeks after the Mullany killings, local shopkeeper Woneta Anderson was shot and killed during a robbery at her store.  All three victims had been shot once in the head. 

The Government of Antigua and Barbuda had called in London's Metropolitan Police to assist with the investigations into the Mullany killings.  Antigua's tourism-based economy was likely to be severely damaged by the killings, unless the case was solved quickly.  Moreover,  Antigua had only one trained forensics officer, who would be under immense pressure without additional expert assistance.   

The Mullany killings were found to be linked to the Anderson killing - all three victims were shot with the same gun.  From the wealth of forensic evidence found at the Anderson crime scene, two local men, Kaniel Martin and Avie Howell, were arrested and subsequently charged with murder. 

After a trial lasting two months, Martin and Howell were convicted of the three killings.  Each man received three consecutive life sentences for their crimes.  At the time of their sentencing, they had yet to be tried for two other charges of causing death by shooting.

One important piece of forensic evidence concerned the partial shoeprints made in blood, which were found at the scene of the Anderson killing.  The forensic examination of shoeprints is a huge subject and impossible to cover in detail in a blog post.  However, here is a report of the shoeprint evidence given at the Mullany/Anderson murder trial, which, I think will give you a good general overview of the topic.

 Shoeprint evidence at Mullany/Anderson murder trial

As is clear from Anthony Larkin's evidence, in order to be able to link a suspect's shoe with a crime scene sole impression, individual features have to be present in both.

Individualisation of a shoe's sole is based upon the knowledge that accidental marks formed during wear are unique.  It is essential that the forensic examiner is well-versed in the shoe manufacturing process, otherwise manufacturing defects could be mistakenly identified as unique wear damage, particularly by an inexperienced examiner.  Cheap footwear is more likely to contain manufacturing defects than expensive brands. 

The surface bearing the shoeprints can affect the quality of the impression.  The wooden floor of Woneta Anderson's store was rough and uneven.  As Mr Larkin pointed out, the damage feature on the sole impression was not as clear as it could have been, because of problems with the surface of the floorboards.

Since footwear impressions are one of the most common types of evidence found at a crime scene, a great deal of research has been carried out to find the best methods for enhancing visible shoeprint impressions and developing latent (invisible) impressions, particularly on difficult surfaces, such as clothing.

Researchers at the University of Abertay in Scotland have recently produced 'the world's first detailed images of latent footwear left on fabrics'.  By adapting and modifying existing visualisation techniques, the researchers hope that their methods will be particularly valuable in cases where no DNA or fingerprint evidence is found.

Read about their work here:

 Shoeprints recovered from crime scene clothing

Finally, a word about automation.  Clearly, the linking of a crime scene shoeprint with an item of footwear is always a task for a forensic expert.  However, reference databases of footwear sole patterns are available for the police and other law enforcement agencies to allow them to identify makes and styles of footwear.  This obviously saves a lot of time and allows a case to move forward more rapidly.

Here are some examples of commercially available shoeprint identification products.

Foster and Freeman's shoeprint identification products

Cape Coral PD in Florida found its shoeprint matching software invaluable in tracking down a serial burglar.  Watch the video here:

I



 

 

If you have enjoyed this blog, please feel free to share it.  Forensics for Writers is on Facebook and NetworkedBlogs.  You can also follow me on Twitter @forensicswrite.

   

The Scent of Death

Last year, the USA was gripped by the Casey Anthony murder trial.  Anthony was accused of murdering her daughter, Caylee, aged 2, and providing false information to the police.  Caylee was not reported missing for a month, and it was a further 6 months before her decomposed remains were found in woods close to her home.  When the jury reached a 'not guilty' verdict on the murder charge, the country was shocked.  There had not been such a controversial verdict since OJ.  I'm sure you will have your own opinions about both verdicts.

 

One of the prosecution witnesses at the Anthony trial was K-9 Deputy Jason Forgey, whose cadaver dog, Gerus, alerted to the scent of human remains in the trunk of Casey Anthony's car and a corner of her parents' back yard.

Watch Deputy Forgey's testimony here.     

The ability of dogs to locate people and objects by scent has been utilised by law enforcement agencies for a long time.  Trained dogs are used primarily for tracking, searching and locating evidence.  Some dogs are cross-trained for more than one task; others are trained to perform a specific function.

There seems to be some variation in terminology for describing and differentiating between dogs trained for particular tasks, but for the purposes of this blog, I'm using the term  'Cadaver Dogs' to describe dogs which are primarily trained as search dogs, but have also received cross-training in the location of dead human bodies.

By contrast, 'Forensic Evidence Dogs' (also known as 'Human Remains Detection Dogs'), specialise in buried bodies, old homicide cases, bone searches, buildings searches, vehicle searches, crime scene searches, small scent sources and residual scent.  Other forensic evidence dogs specialise in searching for firearms, explosives or drugs.

In forensic work, the breed of dog is less important than its ability to learn, interact with its handler and locate a particular scent.  But a search and rescue dog, for example, needs to be robust, like a German Shepherd.

Both Cadaver Dogs and Forensic Evidence/HRD Dogs are trained to locate the scent of death, which is caused by chemical decomposition.  However, because they are not cross-trained, Forensic Evidence/HRD Dogs are never looking for live scent.  They have been taught to exclude fresh human scent and to ignore all animal scents, whether fresh or decomposed, when carrying out a search.  

Working slowly and methodically, a fully trained Forensic Evidence/HRD Dog will not disturb a crime scene nor will it retrieve evidence.  It will also search homes and vehicles without causing any damage.  When it finds a residual scent of a dead human or dried blood, for example, it will alert its handler by demonstrating a particular behaviour, such as standing still and barking, or lying down.

The scent may not indicate the actual location of the remains.  Running water can move the scent away from the grave site.  So although the dog will alert where the scent is strongest, this may be some distance from the body itself. 

The handler of a Forensic Evidence/HRD Dog also has to be highly trained.  If called to court, the handler has, in effect, to testify on behalf of their dog.  So handlers log all their dogs' training and also take courses in orienteering, criminal procedures, report writing, hazardous materials awareness and canine first aid.

So how accurate are Cadaver Dogs and Forensic Evidence/HRD Dogs?  Canine fallibility was alluded to in Deputy Forgey's cross-examination. 

Various studies have shown that handler error and inexperience can lower the recovery success rate from 100% to as little as 57%.  It doesn't matter how good the dog is at locating evidence, if the handler is unable to interpret the dog's alerts properly.

Just like a human, a tired, hungry or stressed dog will not perform as well as when it is fresh, fed and happy.  In fact, a severely fatigued dog may give a false alert, simply because it wants to rest.

Forensic Evidence/HRD Dogs are also employed away from law enforcement work. The Institute for Canine Forensics has been using Forensic Evidence/HRD Dogs to search for Native American burials and cremations on the site of the proposed Tule Wind Energy site in the McCain Valley, California.

Here is a video of one of the dogs at work.
       

Don't forget, you can find out when I post a new blog  - and much more - by following me on Twitter @forensicswrite.