SciBlogs

Archive January 2010

The nasty job of identifying victims of mass disaster Anna Sandiford Jan 29

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How are victims of disasters like the Haitian earthquake identified if they are unrecognisable when they’re recovered from the debris? By using forensic science techniques.
As with the South East Asian tsunami of 2004, Hurricane Katrina in 2005 and so many other situations, dozens of bodies need to be identified as fast as possible.
I heard a forensic dentist talk about the terrible working conditions in Indonesia where bodies were stored in unrefrigerated shipping containers (no refrigeration units), waiting to be identified – time was clearly of the essence for multiple reasons – closure for the family before the bodies rot, getting through the bodies before they rot so badly that they’re difficult to handle. Because they had such limited facilities, the dentists and anthropologists rigged up a portable x-ray machine to some school chairs they found in the debris so that they could elevate the machine high enough over the bodies so it could be operational. Bodies like these are not only damaged but often caked in mud, making visual identification not only traumatic for the family but also extremely difficult from a practical perspective and sometimes impossible.
In situations of mass disaster, relatives of the missing also provide DNA samples or are asked to bring along hairbrushes or toothbrushes of their family members so that DNA samples can be collected and compared with cadavers. Dental records are acquired where possible.
I was on a training course in July 2005 with three of the first firefighters who had attended the London Tube bombings two days earlier – they talked about the lack of air in the Tube tunnels, the ambient heat, the smell, the hours they spent down there logging the scene, searching for people and finding bodies. I talked with people whose office windows had been blown out by the London bus bomb in Tavistock Square – crime scene examiners came and took swabs from their office furniture and the roof because knowing the extent of the damage (i.e. spread of the human DNA) helps map the bomb site and determine things like location of the bomb relative to the passengers – vital for working out what happened and possibly for use in prosecution. I don’t think the people who had to go and work in that office will ever look at the walls in the same way again – even the best crime scene cleaners can’t wash away what stains the mind.
The people who go to scenes of mass disaster are a rare breed. CSI makes this job look sexy. It’s not.

Meth driving Anna Sandiford Jan 26

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How hard is it for a Police officer to determine whether a driver might be off their trolley because of methamphetamine abuse?  Some might say that if you see it often enough, you recognise the signs.
How hard is it for a forensic toxicologist to reconcile different driving behaviours as being attributable to meth use?  Possibly very difficult, if no blood sample is taken.  However, New Zealand’s law now allows for a blood sample to be collected from drivers suspected of driving whilst impaired through drugs (see previous posts: Drug driving and impairment testing, Roadside impairment tests; drug driving, Don’t accept the forensic science at face value).  Which is just as well, given the enormous variation in behaviours that can be exhibited by meth users.
I would expect most people in NZ would think that a driver who was on P (pure methamphetamine) would be tanking down the motorway at 150 kph with the Police in hot pursuit, as per last year’s events involving the accidental death of a courier driver who was caught in the cross-fire between Police and an armed driver. However, an article in last month’s Science & Justice shows just how varied the effects of P can be.
The article’s author, Nikolas Lemos*, writes of two separate cases involving drivers being stopped by Police.
The first case involved a relatively placid, co-operative man who drove somewhat erratically but was slow (only about 30 miles an hour) and was tail-gating the car in front. Police asked him to stop and he did.
The second case involved the Police in a high-speed car chase with a driver and a stolen sports utility vehicle. After racing along roads at speeds in excess of 100 miles an hour, the driver then leapt from the moving vehicle, leaving a female passenger to crash, along with the vehicle, into police cars. Police chased the driver and tried, unsuccessfully, to subdue him with a conductive energy weapon (which I assume means a Taser). After being Tasered (is that a real word?) another two times, he was dragged kicking and screaming into custody.
Two more dissimilar descriptions of P users you couldn’t imagine but the blood methamphetamine concentrations of both drivers were comparable as were their heights and weights. Just goes to show just how unpredictable P can be.

* As the article is behind a subscription wall, the full reference is: Lemos, N. 2009. Methamphetamine and driving. Science & Justice, 49(4), 247-249.  Abstract: Methamphetamine incidence in driving under the influence cases in the City and County of San Francisco is a significant and on-going challenge.  Two methamphetamine positive driving cases are presented herein demonstrating some similarities in observed signs and symptoms and drug blood concentrations but which are also characterised by very different driving styles and behaviours towards the police officers when encountered on the road.

The article also discusses other issues such as the field impairment tests and analytical results.

Catching a wolf serial killer Anna Sandiford Jan 22

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Wildlife forensics is an expanding area of forensic science – there is even a separate session in the upcoming Australia & New Zealand Forensic Science Society 20th International Symposium in Sydney this September.
Seeing as this subject is gaining wider acceptance, I thought I’d share the story of the recent arrest of an Italian man for being a serial wolf killer. Wolves have been a protected species in Europe for some time and have been protected in Italy since the 1970s. Unfortunately, a number of wolves were found killed and sometimes mutilated (the muzzle being missing from at least one) in the Genoa region. A man was eventually arrested and from him was seized a necklace of teeth. The teeth were sent to the Italian Institute for Environmental Protection and Research (ISPRA) where wildlife specialists extracted DNA from them.
As with any case like this, unless there is a database against which to compare results. the results can themselves be more or less meaningless. However, because of the European focus on collating information there is in fact a DNA database for wolves and other large predators that is used to assist with population monitoring. The DNA is gathered from many sources including cadavers and faecal matter (not forgetting other possible sources such as fur, skin, bones, etc., etc.).
Six separate wolves were identified from the necklace using the DNA database. Obviously not all killers wear their victims teeth – at least not usually of the human variety – but keeping mementos of hunting is not at all unusual and it makes perfect sense to use trophy items to attempt to link a possible offender with an offence. As this is totally outside my area of knowledge I have no idea how much wildlife DNA is being monitored or tracked throughout New Zealand and Australia but I assume it would be a very handy tool for Customs and MAF – perhaps I’ll be able to report more after I’ve attended the conference (particularly if someone wants to pay the AU$2500+ that it’s going to cost…).

Cocaine on banknotes Anna Sandiford Jan 10

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I was surprised at a news article in the English MailOnline, which states that Every British bank note is contaminated by cocaine within weeks of entering circulation. I wasn’t surprised about the cocaine issue, but about the fact that the media seemed to think this was new or unusual.

I’ve been working on cases involving drug traces on banknotes since 2002 and even back then 95% of English banknotes were contaminated with traces of cocaine. To my mind, the most comprehensive database dealing with drug traces on banknotes is compiled and maintained by a company in the West Country of England. When I left England in 2008, practically 100% of banknotes in the database were contaminated with cocaine (and not just contaminated but high levels of contamination), less were contaminated with MDMA (from Ecstasy) and amphetamine, and less still with diamorphine (from heroin) and THC (from cannabis).  The company is question is not one of the mainstream prosecution laboratories but a standalone organisation that has developed specific equipment to deal with analysing traces of drugs on all sorts of items including vehicles, clothing, mobile phones and, of course, banknotes.

It should be remembered however that the traces of drugs we’re talking about here are so minute that they can’t be seen with the naked eye.  To put it into perspective, if one took a grain of salt and divided it into 1,000 pieces and then if one took one of those pieces and divided again into 1,000 pieces, this is the level of contamination that the anaytical equipment can detect – it’s teeny, teeny tiny.  The other way to look at is if the total amount of drugs present on one million English banknotes (each contaminated with this small weight) was bulked together it would amount in size to no more than a single grain of salt.

Drug traces on banknotes can be extremely valuable for assisting Police and Customs to determine whether or not seized quantities of money have been involved with the drug trade but cocaine has always been a difficult one to interpret.  Wouldn’t it be great if the technology could be applied in New Zealand, given that there is such a problem with P here?

UK from space – cool Anna Sandiford Jan 08

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Not even vaguely related to forensic science but it’s a great photo from this link:

A country at a standstill

Rubbish criminal – an example Anna Sandiford Jan 08

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I don’t normally consider anything written by the UK’s The Sun newspaper as overly credible but this story just begs to be told (assuming that it’s true).  A man placed a webcam in a store changing room so that he could cop a free look at people trying on the new season’s Spring collection: Peeping Tom caught in the act. He placed the camera in an ASDA supermarket store, which is like placing it in a Warehouse changing room.  As he placed the camera in situ he managed to take two photographs of himself.  Staff in the store noticed the camera within half an hour and notified the Police.  In addition to the photo he took of himself, it looks from those photos like he wasn’t wearing gloves at the time he placed the camera – maybe there is someone out there who doesn’t watch enough crime scene TV programs.

He hasn’t been caught yet but when he does (and I can’t see how he won’t – he’s plaster over one of the most popular tabloids in circulation), it’s a gift to the Crown Prosecution Service and it’s a cautionary tale: there are people out there who will do this sort of thing – and some of them will do it better and not get caught.  Be warned – shopping is bad for you!

When others are fleeing, UAE embraces DNA database for ALL Anna Sandiford Jan 08

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In a world where Western countries are running from the tide of DNA data that is washing over them, the United Arab Emirates seems to be taking a totally different stance.  At the moment, the UAE only collects samples from suspects or convicted criminals.  What they are looking at doing is expanding the DNA database to include every citizen (and I use the term in a colloquial sense, not a Border Control sense) – so that’s the entire population, both local and expatriate.  The thinking behind this is to assist with victim identification following mass disasters (natural and, presumably, man-made) and also to assist in missing persons cases.  They also apparently consider that it will drastically control crime,  reduce the number of unnecessary suspects and innocent suspects and reveal the real criminal in a case faster than at present.

The samples will start being collected within the next year, starting with the youngest end of the population, taking 1 million samples per year (that’s more than 2,700 each day).  Rather than write new legislation, the population could just be issued with a Security Directive to give a sample.

In a country with a population around the 4 and a half million mark and expanding rapidly, that’s a lot of DNA data, given that they currently have only 5,000 profiles on the current database .  I just hope their statistical interpretation software is up to the job.

Crime DNA databases should be independently examined Anna Sandiford Jan 07

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Who has ever analysed the data in national DNA databases?  Courtesy of programs like CSI and the news/media, we all know that DNA can be an extremely powerful tool in crime solution.  When a sample from a crime scene is compared with a sample from an individual it should be the easiest thing to be able to say whether or not they originated from one and the same person, shouldn’t it?

In forensic science (and many other areas of science), without a solid and reliable database, interpretation of results can be troublesome or even meaningless.  So who has checked all the databases that have been built up by Police and prosecution agencies over the years?  Who checks them to make sure that the data is correctly entered or that the statistical basis for the interpretation is still correct and appropriate?  As it turns out, it doesn’t appear that anyone is really doing it, particularly in relation to the USA.  An article in this week’s New Scientist demonstrates this: Unreliable evidence? Time to open up DNA databases. Most of the world’s DNA results (and I am talking about those relating to criminal casework) are interpreted using the results of relatively small studies undertaken during the early years of DNA forensic casework.

The opening two paragraphs of the article cover it quite nicely, I think: “When a defendant’s DNA appears to match DNA found at a crime scene, the probability that this is an unfortunate coincidence can be central to whether the suspect is found guilty. The assumptions used to calculate the likelihood of such a fluke – the “random match probability” – are now being questioned by a group of 41 scientists and lawyers based in the US and the UK. These assumptions have never been independently verified on a large sample of DNA profiles, says the group. What’s more, whether some RMPs are truly as vanishingly small as assumed has been called into question by recent insights into DNA databases in the US and Australia. I find that slightly unnerving because I know from professional experience that if a DNA result is presented in court, it’s unbelievably difficult to shake anyone’s faith in the result.

I’m not suggesting that there is anything significantly wrong with any of the DNA databases but they should be open to examination by independent scientists so that the reliance that is placed on DNA interpretations can be shown to be well-placed. It makes the results relevant and reliable, which is important for acceptance as evidence in court.

The article does a good job of explaining the problems associated with DNA databases, describing three possible reasons why some profiles on the reference databases match one another (if they are all from different people then they should all be different): 1. duplication of the same profile in the database; 2. assumptions about frequency of occurrence of allelles in populations (see article for definition); and 3. the large number of relatives that may be on a given database (people who are closely related share more common areas of DNA in their profiles than people who are unrelated, which is logical). Particularly in relation to the latter point, if only a partial profile is obtained from a crime scene (i.e. only part of the DNA profile ‘picture’ can be detected), the chances increase of the sample matching more than one person’s database profile. (N.B.  There are essentially two sets of information in DNA databases – DNA profiles obtained from crime scene samples (so initially we don’t know who is the source of them) and DNA profiles taken from actual known people, usually suspects (depending on the legal jurisdiction)).

Of course, the converse of this is that if a DNA profile in the database has been incorrectly entered in some way, the chances of getting a “hit” on a cold case are also affected (a “hit on a cold case” is where re-examination of evidence is undertaken some time after a crime was committed, usually years afterwards, and a newly-acquired crime scene DNA result is run through the database for the first time.  If the crime scene profile matches a person’s profile already on the database, you’ve got a “hit”).  If the data’s not correct in the database, a ‘hit’ might become a ‘miss’.

The big question is whether the FBI will allow a group of independent scientists to review the USA’s CODIS database – and the answer at the moment is no.  This to me is a fairly typical attitude of prosecution agencies for this kind of access.  I can understand their reluctance in a way but I would think it would be a better thing to have it reviewed now rather than wait for a case to demonstrate a monumental stuff-up and get beaten with the consequences later, particularly to have it reviewed by people who would sign confidentiality agreements and then look at the data as a whole rather than focussing on one case where there may well be a problem.  As the closing commentary says, “Without external scrutiny of the databases, doubts will remain….All of this can be resolved by letting scientists have access to the data to do what they need to do.“  We all have our dreams, and I hope theirs comes true.

[The New Scientist article is based on a Science article, December 2009, v.236, p.5960]

55 year old murder – solved Anna Sandiford Jan 04

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Much is made of the traditional techniques used in forensic science, and rightfully so.  However, sometimes the power of the internet and what the general public is doing with it cannot be underestimated in solving crime.

A 55-year-old murder case from Boulder, Colorado, has finally been solved using a combination of media (TV’s “America’s Most Wanted”), exhumation, DNA extraction, forensic anthropology, forensic artistry and someone watching case progress over the internet (Victim of 1954 Homicide Case, “Boulder Jane Doe,” Identified).

The battered body of a young woman was found on a river bank near Boulder on 8 April 1954 but she was never identified and she was later buried in a simple grave.  Eventually, after prompting by a local historian, Silvia Pettem, the case was re-investigated, funds were raised, the body was exhumed in 2004 and a DNA profile was obtained.  An artist’s impression was created and shown in the media, including on “America’s Most Wanted”.  Silvia Pettem kept the case alive with a website (www.boulderjanedoe.com/Jane%20Doe.html).

After a long time, a woman came forward to suggest that the deceased could be her long-disappeared aunt.  The woman who came forward had been following the case on the internet and eventually decided it was worth a punt to suggest her aunt’s name.  A DNA profile was obtained from another aunt and it came up with a match for the deceased.

Everyone thinks “it couldn’t happen to me and mine”.  In this case, a woman who was watching the case over the internet thought “maybe it could be me and mine”.