How to remove a lightbulb using a kid’s dart is described as “a high tech process to remove a light bulb without damaging latent prints using a toy dart” (some dry humour is always a good thing in forensic science) – this is the sort of forensic technique that is not only interesting but extremely useful….and it’s exactly how it sounds!

Other useful videos on the same page include How to lift a dusted fingerprint off a body or a live person and How to use a stun gun as an electrostatic dust lifter. These videos are short and highly informative. Recommended viewing for the interested and the budding crime scene investigator.

I often receive queries about forensic DNA – how to get a job, how it works, what it’s all about.  As a result, I have trawled about the web quite a lot and encountered The DNA Initiative. It’s an American website, so some things are not immediately applicable to other countries (such as Statues and case law, but they’re still interesting).  Overall ,it seems to be a comprehensive site that explains all about forensic DNA including how it can be applied in Cold Case Reviews.

One of my work-heads is as a Palynologist, which means I study pollen, spores and other microscopic material that remain in sediments after they’ve been chemically treated to remove extraneous material.  For forensic work, we might be limited to sediment scraped from the knee of a pair of trousers or perhaps pollen collected from the heads of cannabis plants, but any sort of sediment can be examined for pollen.
For geological/archaeological samples, lake sediments and peats are the best in terms of preservation state, abundance and variety.  It is therefore extremely heartening to see that palynology has been able to help in determining the extinction mechanism of mammoths and other large mammals during the last Ice Age, which ended approximately 10,000 years ago (depending on one’s global location) – see Mammoth dung unravels extinction. The study indicates a gradual decline in large mammal numbers, not a catastrophic extinction a la the dinosaurs at the Cretaceous-Tertiary boundary 65 million years ago.
Scientifically, it’s an interesting study but from a general perspective I still find it strange that people are surprised that the large mammals are probably more than just a pretty addition to an African landscape but have actually been significant in it’s development. I’m pretty sure David Attenborough’s known that for years.
It’s also reassuring that analysing excrement can add so much information to our knowledge – an archaeologist I know has spent years analysing coprolites from Maori sites. It’s fascinating what we can learn from pooh.

Blood pattern analysis (BPA) is an area of forensic science that is extremely important but extremely under-rated – people seem to have a misconception about how easy it is to “read” blood patterns (no doubt not helped by CSI!).  To become proficient in blood pattern analysis requires more than just a few tests drips cast down a wall or onto paper.  Understanding the variability in pattern (or lack of) created by direction, velocity, flow, depositional surface…. are crucial to correct interpretation of blood patterns.  As with any other area of forensic science, specialised training is required plus considerable experience backed up with advice and peer-review.  It’s not the sort of thing that can just be Googled for a quick answer.

Finally I have managed to find a good online resource that details how to record blood patterns: Documenting Bloodstain Patterns Through Roadmapping .  It may sound ridiculous but you’d be amazed at how poorly blood patterns are recorded in casework. As the article states, “As the old adage goes, “a picture is worth a thousand words.” However, in the field of crime scene investigation this saying should be changed to “a properly taken picture is worth a thousand words.” Never is this more true than when documenting bloodstain patterns at a scene. Proper documentation of a crime scene, and bloodstains specifically, verifies the integrity of the scene and the evidence within it; provides quality presentations for subsequent courtroom testimony; and allows for outside analysis by other experts. The fundamental goal of documenting bloodstain patterns is to accurately depict the patterns as you found them.” One of the key indicators of a good crime scene examiner is the ability to record information from a crime scene so that it can be viewed at a later date by individuals who have not attended the crime scene so that they, in turn, will be able to understand what was present and, if necessary,re-interpret the patterns.  Some people could learn from this….

The following article appeared in Science Daily on 17 September 2009.  It seems that this field of expertise, bitemarks, has fallen foul of the usual criticisms of unusual evidence types – the lack of an adequate, representative database for interpretation of information in a given case.  Without such a database there is no real way to objectively and statistically interpret scientific findings.   Attempting to present such scientific findings as evidence in court often fails because the science does not meet the basic criteria for evidence to be presented in court; depending on the jurisdiction that may be the Daubert or Frye rules or just whether the evidence is reliable, relevant and repeatable. This criticism has been levelled at several areas of forensic science notably, in my career anyway, drug traces on banknotes.

I also remember there was a famous case in the UK where an IRA bomber ate an apple at a “location of interest”, discarded the core and the core was recovered by the Police.  His dental alignment was compared with the apple core and he was positively identified as being the apple eater.  From distant memory, this linked the apple-eater into a significant terrorist event.  This was in the days before DNA. In today’s courtroom, it’s unlikely that the apple bite would be accepted as evidence in isolation; corroborating evidence would be required because, on its own’ it’s circumstantial and potentially more prejudicial than probative.

On a lighter  but practical note, I’m glad they used stone teeth in the following study, rather than live people to bite the cadavers….

“Bitemark evidence and analysis should be approached with caution, according to study

Against the backdrop of last week’s [US] Congressional hearing into the future of forensic science, researchers from the University at Buffalo’s Laboratory for Forensic Odontology Research in the School of Dental Medicine, have published a landmark paper on the controversial topic of bitemark analysis.  The Congressional hearing focused on the findings of a National Academy of Sciences (NAS) report on the scientific basis of forensic disciplines. Among the pattern evidence fields (fingerprints, tool marks, etc.) that were reviewed in the NAS report, bitemark analysis received critical commentary. During the hearing, Innocence Project co-founder Peter Neufeld introduced Roy Brown, wrongfully convicted on bitemark evidence and later exonerated through DNA analysis.

In anticipation of the NAS report, the new UB study published in the Journal of Forensic Sciences challenges the commonly held belief that every bitemark can be perpetrator identified.  “Bitemark identification is not as reliable as DNA identification,” explains the study’s lead author Raymond G. Miller, D.D.S., UB clinical associate professor of oral diagnostic sciences.  “With DNA, the probability of an individual not matching another can be calculated,” he says. “In bitemark analysis, there have been few studies that looked at how many people’s teeth could have made the bite.”

Miller’s co-authors include UB’s Peter J. Bush; Robert Dorion, D.D.S., DABFO, UB adjunct professor of oral diagnostic sciences; and Mary A. Bush, D.D.S., UB assistant professor of restorative dentistry. Dorion is the editor of the only comprehensive textbook on the subject of bitemarks in forensic science, Bitemark Evidence: A Color Atlas and Text, and is currently the odontology section representative to the board of directors of the American Academy of Forensic Sciences.

The current study investigated three main questions: is it possible to determine biter identity among people with similarly aligned teeth; is it possible to determine how many individuals from a larger sample might also be considered as the biter; and, if there is bite pattern distortion, is it enough to rule out a specific biter while still including a non-biter?

To answer these questions, the researchers gathered 100 stone dental models (replicas of the dentition), which were measured and divided into 10 groups based upon the misalignment patterns of the teeth. After randomly selecting one model from each of the 10 groups, the researchers impressed bitemarks on cadaver skin. After the bitemarks were created, they were then photographed and the indentations were compared to the dentitions using overlays created with photographic software.

The authors are one of the first to use a human skin model rather than animal models or non-elastic biting substrate, such as wax or Styrofoam. Current human subject restrictions limit experimentation on living subjects.  “Living bitten tissue may bleed or bruise,” explains Miller. “The initial bitemark indentations rebound shortly after infliction often leaving a diffuse bruising that may be difficult to measure accurately. The indentations produced in our study represented the best conditions for measurement.”

The results indicated that when dental alignments were similar, it was difficult to distinguish which set of teeth made the bites. Distortion noted in the bitemarks allowed matches even from different alignment groups. Therefore, the researchers concluded that bitemarks should be very carefully evaluated in criminal investigations where perpetrator identity is the focus of a case.

As Miller notes, “In the past 10 years, the number of court cases involving bitemark evidence that have been overturned led us to question the reasons for the erroneous bitemark identification. It’s important to recognize the serious consequences of a misidentification for the accused, the victim, the families involved, the justice system and the possibility that the perpetrator is still at large.”