Forensics Science

Resting on shaky ground: did DA Doorley mislead a jury on faulty DNA evidence?

Some truths are axiomatic. They’re ideas we hold as being so solidly true, we never bother to examine them too deeply.

The concept of “DNA evidence” as the fool-proof smoking gun is one of these axioms. We understand that your personal DNA encoding is responsible for determining your sex, hair color, eye color and even your risk of having a heart attack. We know that, when a person interacts with a crime scene, there’s a distinct possibility that they may leave behind substances from which DNA can be sampled and a match found. There’s even new technology aimed at potentially reconstructing your face from DNA, to help police search you out.

But is DNA evidence presented in court really so iron-clad? What exactly constitutes a “match” by forensic standards, and how close can that match be to the true criminal? These questions were put to the test just recently in the appeals trial for Howard Wright, charged with the 1995 rape and murder of Patricia Daggett. The conviction was ultimately upheld on a 3-2 vote, but the two judges that dissented point out that the DNA evidence was nowhere near as conclusive as they contend then Assistant District Attorney Sandra Doorley made it seem. Indeed, based on court documents, it very clearly was not. The dissent reads in part:

As the majority notes, the People “presented evidence that . . . defendant’s DNA could not be excluded from various pieces of evidence recovered [from the victim’s vehicle].” At trial, the People’s forensic expert, who analyzed defendant’s DNA sample, described the two types of DNA testing used in this case—mitochondrial DNA analysis and YSTR DNA analysis…

The People’s forensic expert acknowledged the two above-mentioned types of DNA analysis at trial, but she did not speak at length about a third type of DNA analysis—autosomal..

How could an analysis of DNA evidence not point solidly to a single individual? The dissent notes that the sample could not have ruled out the victim’s husband, nor could it rule out the second alleged accomplice in the crime, Christopher Gifford. And what are these three types of DNA testing?

The DNA of DNA forensic testing

To unravel this mystery, we first need to understand that not all DNA in your body is the same. There are two types: nucleic DNA and mitochondrial DNA.

Nucleic DNA is a combination of information from your genetic parents, which is passed to you, and is responsible for the you-building that we all understand. Mitochondrial DNA is passed more or less unchanged from your genetic mother to you. Mitochondrial DNA does not contain enough information to be used to pinpoint a specific individual, but can be used to broadly exclude individuals who simply do not match.

That leaves us with nucleic DNA. But here again, there are two different types of testing, YSTR and autosomal. YSTR tests are performed on the Y chromosome and therefore only possible in male individuals. But since the Y chromosome is passed intact from father to son, all individuals of a specific paternal line – which could potentially be quite vast – will have similar or exactly the same YSTR results.

Autosomal DNA testing is the closest thing in the forensic arsenal to the “smoking gun.” In autosomal testing, 22 out of the 23 pairs of chromosomes that make you what you are can be tested. The 23rd pair is, of course, the sex pair for which YSTR is used. Here is the evidence which sometimes boasts a 1-in-a-billion accuracy.

Then what of Mr. Wright’s sentence?

Regardless of which method of testing is used, the results boil down to a statistical analysis and professional judgement of the facts of the case. And none of these types of evidence is easy to get in the first place. DNA like all living material is delicate and easily destroyed at the scene of the crime, by investigators or even by the lab.

Mitochondrial and YSTR testing can certainly be used to exclude a suspect from consideration, assuming that their DNA signatures differ significantly enough. But they don’t do much to identify a specific suspect, especially as in this case, where multiple persons involved in the crime all fit the same basic profile. Only autosomal DNA testing can positively identify a single individual, but that requires a working, undamaged sample of all 22 required pairs.

The dissent for Mr. Wright’s appeal says that the People’s forensic expert never spoke “at length” about autosomal DNA evidence. Was that because that evidence was not conclusive, or not possible to obtain? Nobody says.

Other evidence presented in the case, as recounted by the appeal ruling, is deeply suspicious but circumstantial. Wright was seen in Daggett’s car with her prior to the murder; the prosecution proved that Daggett was raped in the car; eye witnesses saw Wright in Daggett’s car the next day. None of these facts would have been usable for a conviction on their own, without DNA evidence. But the DNA analysis was itself dubious and inconclusive: it implicates three potential suspects, one of whom was never on trial.

The real problem here is not whether the DNA matched one individual suspect. The real problem seems to be that the fate of our justice system was in this case settled by a 3-to-2 decision in which the majority seems to whistle past a very large graveyard. The majority waves a fairly vague hand at the DNA evidence and concludes, based on circumstantial evidence, that a “reasonable person” might have found Mr. Wright guilty. In the absence of the DNA, is that really true?

If sympathy for the convicted is hard to come by, it is worth considering the implications of a 3-to-2 decision in the opposite direction. Had the flimsiness of the DNA evidence been the thing that overturned the conviction of Howard Wright, how many more men in how many more jails might have been set free, possibly erroneously, on the basis of dubious forensic evidence gathering?


Buffalo researchers think schizophrenics might be cured with anti-smoking drugs

Schizophrenia is a cypher to science. It is an inherited disease, yet it does not go strictly from one generation to the next. It may skip a few. There are even arguments that schizophrenia may be caused by environmental instead of genetic factors. But one thing most schizophrenics have in common:

They smoke. A lot.

Researchers at the University of Buffalo believe that schizophrenics smoke because nicotine is a form of self-medication, and that by working with smoking cessation drugs (nicotinic agonists, they call that), doctors may be able to help repair cognitive functions of the sufferers.

How is this possible? They believe they have discovered a single genetic pathway, or series of DNA segments that work together, that controls as many as 160 different traits, all associated with the disease:

 “How is it possible to have 100 patients with schizophrenia and each one has a different genetic mutation that causes the disorder?” asks Stachowiak. “It’s possible because INFS integrates diverse neurological signals that control the development of embryonic stem cell and neural progenitor cells, and links pathways involving schizophrenia-linked genes.

“INFS functions like the conductor of an orchestra,” explains Stachowiak. “It doesn’t matter which musician is playing the wrong note, it brings down the conductor and the whole orchestra. With INFS, we propose that when there is an alteration or mutation in a single schizophrenia-linked gene, the INFS system that controls development of the whole brain becomes untuned. That’s how schizophrenia develops.”

The link between smoking and schizophrenia is well-established. Because there is such a strong, common link between smoking and this otherwise disparately symptomatic disease, researchers believe that nicotine and nicotinic agonists may be affecting this pathway.


Did Facebook just talk you into voting for a psychopath?

Yeah, yeah, yeah. You think your vote comes after careful deliberation and analysis. You think your vote is an intelligent one. You studied the candidates, you know the issues, you made the right choice.

Bullshit. You probably voted straight across the ballot, Democrat or Republican.

Moreover, we’re finding out more and more that our political identities are very much governed by forces that are quite beyond our control. Genetics, for example, affect our psychology  and predispose us to becoming liberal. Scientists also studied twins – including those separated at birth – and found that while many broad-strokes political concepts might be informed by their parenting and social interactions, many more seemed to be genetically linked.

Everyone is pissed at CNN’s gutless, sloppy reporting about studies linking women’s menstrual cycles to their voting preferences, but really? At the end of the day, we’re all just bundles of synapses to be tickled, poked and prodded in ways that will make us do shit. Our genetic code says so; our FourSquare checkins confirm it. Why would something as repetitive as a menstrual cycle not affect one’s voting habits?

And speaking of the remote control of our nominally free will: Facebook.

In the last midterm election of 2010, scientists conducted a study on Facebook, wherein groups of people got nags to go vote in what are typically low turnout elections. The result was higher turnout among those who were actively asked to vote, especially those who also had friends who said they voted as well. Voting, it appears, may be every bit as viral as cat videos.

Let us not speak falsely, now.

And just who is it you think you voted for? The most reasonable candidate? The one with the best handle on the economy? Foreign policy?

Nope. Turns out that the traits most often attributed to successful politicians are also common sign posts for… psychotic behavior. That’s right. In particular, the social trait of “fearless dominance,” or being a huge dick, is quite common among both groups. The leader of the study helpfully stresses the following:

“Most psychopaths end up being pretty unsuccessful and maladaptive, and they end up in prison, which is usually where psychologists study them,” Lilienfeld said. “Even though the psychopathic personality as a whole shebang is not a good thing to have, this study raises the interesting possibility that at least some traits of this condition — especially those linked to lack of social and physical apprehensiveness, immunity to stress, and resilience — might be adaptive in real-world settings.”

Ah, yes. Because who has ever heard of a politician going to jail?

So, I’m really glad you voted. Honestly. But now that you have, you can sit back and relax, because you never really had a choice in whom you voted for. The universe is a rigged game of controlled explosions and we are merely the flotsam of inter galactic collisions. Our opinions are statistical, our lives artifice and our impressions of ourselves merely the deluded ramblings of monkeys on drugs in cages. Happy Election Day!


Bioarcheology: scientists study the African Diaspora and slavery’s genetic trail

Nature reports today on the beginnings of a vast new historical project aimed at fitting together the missing pieces of the African slave trade’s effects on the victims. One group will study bones of enslaved Africans for demographic, quality of life and chemical analysis information. Another will study written records of slave trade. But the largest focus of the study is on studying the DNA evidence in living populations of French Guiana to reconstruct the origins of the original slaves.

The study has the potential to bring up a host of uncomfortable subjects. For example, one lead researcher notes that the extent to which African slaves and their white masters may have interbred. And since much of the current historical record is “fragmented,” as another researcher put it, we may find that the routes to the Americas are not as straight as we once thought.

For more information on the study, see the Nature article posted below:

Filling in the gaps in the slave trade : Nature News & Comment.