Recent Developments in Forensic DNA

The use of DNA in forensics continues to expand. Last year, James Cass reviewed the current system of forensic DNA profiling in the U.S., including CODIS (the Combined DNA Index System, the FBI’s integrated DNA profiling program), the controversial practice of partial/familial searching, and calls from President Obama and others to collect DNA profiles for all Americans in a national database. He posted follow-up pieces focused on advance DNA collection under Katie’s Law, the growing backlog of DNA samples, and familial DNA database searching, which gained support after it facilitated the arrest of the elusive serial killer in California known as the Grim Sleeper.

A number of newer developments have caught our attention.

The Council for Responsible Genetics (CRG) in Cambridge, Massachusetts and GeneWatch UK teamed up to announce a new online resource called National DNA Databases last month. The website focuses heavily on the controversial topics of familial searching and advance DNA collection (requiring a DNA sample of all arrestees, when charges are filed, or as part of a plea bargain). In addition to information about 56 nations operating DNA databases around the globe (inaccessible to the public), this resource includes U.S. maps showing “State Rules on Partial/Familial Searching” and “States Collecting DNA Samples from Arrestees,” (same link) both discussed below.

Partial DNA Matching Expanding. Law enforcement officials typically search DNA databases for a profile that matches DNA from a crime scene sample. Partial or familial searching of DNA databases is a new method that allows the searcher to detect profiles that share some aspects of the crime scene DNA when no exact match is found. In states where this type of search is permitted, a partial match may generate new leads through investigation of close relatives of the person whose profile was in the database. All convicted felons and members of the military have been profiled in the U.S. databases for many years now, and increasingly many others are also included (see below). Partial matching effectively broadens the investigator’s castnet to reach close genetic relatives of everyone in the databases. Those family members can then be openly investigated or DNA tested through surreptitious sampling (considered legal because trash is public domain with no associated privacy rights, and thus a discarded coffee cup is fair game).

Last year Cass reported data from 2009 indicating that at least 15 U.S. states allowed the use of partial matches, but at least 10 of those required that the partial match be discovered unintentionally. It can be difficult to determine which states are actually utilizing this tool, because it often takes time to develop an official policy. However, the CRG website says that today at least 15 states allow intentional partial match searches, at least 6 allow a partial match to be utilized if discovered unintentionally, at least 5 have a “draft policy under review,” and 13 are operating under unknown policies. Only 11 states continue to prohibit partial matching and familial searching altogether.

Critics point out that partial matching is problematic for several reasons. For example, being related to a convicted felon or member of the military has no bearing on one’s own innocence. Vocal Maryland defense attorney Stephen Mercer says, “If my brother’s DNA ends up in the database, and he’s forfeited his privacy rights by becoming a convicted felon, has he also forfeited my privacy rights as a wholly innocent family member?” Likewise, members of the military do not intend to compromise their relatives’ genetic privacy simply because they agree to submit their own DNA samples.

Another problem is that the U.S. African-American population currently comprises a disproportionately large percentage of the databases because of their overrepresentation in the prison system. Therefore, partial matches leading to relatives of those in the databases will also disproportionately target African-Americans for criminal investigation. According to CRG, although African-Americans are only 12% of the U.S. population, their profiles constitute 40% of the Federal database. Creating a national database with DNA profiles for all U.S. citizens would go a long way toward solving this problem, but critics of that plan object on the grounds that requiring U.S. citizens to submit DNA is an unconstitutional invasion of bodily privacy.

On the other hand, familial searching is in fact an effective crime-fighting tool. The practice has greater public approval in the UK, where the technique famously led to the identification of the “Shoe Rapist” because of a partial match with his sister. The percentage of the total UK population represented in the national database is much greater than in the U.S. Now, a British MP is calling for DNA testing of the entire male population of Bristol, around 250,000 people, to help solve the murder of Joanna Yeates in December, 2010. Media reports indicate that there was no evidence of sexual assault, but that saliva was found on the exterior of Ms. Yeates’s clothing. And when predators remain at large in the U.S., such as in the Virginia case of Morgan Harrington and the recently announced serial killer in New York, familial searching increasingly gains support in this country too.

Advance DNA Collection Also Expanding. Advance DNA collection in the U.S. also continues to expand at various stages of the criminal procedure timeline. Previously, only persons convicted of felonies were required to submit DNA samples for federal databases. In fact, until 2004, federal law prohibited maintenance of DNA profiles in the databases for anyone who was subsequently acquitted. A very different picture exists now, according to CRG:

Today, 44 states collect DNA from anyone convicted of a felony, 39 states collect DNA from those convicted of certain misdemeanors, 28 collect DNA from juvenile offenders, 6 states collect DNA of all individuals arrested and some states (such as California) have started to retain DNA from individuals identified as “suspects.” Still other states such as Louisiana and New York have been discovered to have “offline” DNA databases including DNA samples and profiles taken from victims or suspects never charged with a crime.

Of particular interest is New York, where Governor David Paterson proposed legislation last year that would require even those convicted of low-level misdemeanors to submit DNA samples. That proposal has been moving slowly in the state legislature, but in the meantime, State Division of Criminal Justice Service Acting Commissioner Sean M. Byrne has issued a letter “strongly encouraging district attorneys in the state to require a DNA sample as a condition of all plea bargains.” Also in December, 2010 in California, Orange County officials unanimously voted to renew the District Attorney’s “spit and acquit” DNA collection program for another year.

Other Expansions of Forensic DNA. Massachusetts gave us the most surprising legal event of 2010 in the world of forensic DNA. The state’s highest court, the Supreme Judicial Court, affirmed the indictment of a DNA profile as a proxy under the name “John Doe” to circumvent the 15-year statute of limitations for rape, which was set to expire in that case. Critics of this decision point out that it essentially does away with the statute of limitations for cases with DNA evidence. The office of the state Attorney General, however, says it will “ensure that the clock does not run out on the use of DNA evidence to hold dangerous predators accountable for their violent acts.”

In newer technologies, Dan Vorhaus wrote last year about the potential use of DNA from a suspect’s pet or the suspect’s bodily bacterial signature to investigate non-human DNA profile evidence. Using a similar rationale, some businesses in the Netherlands have been equipped with a “device that sprays a fine, barely visible mist laced with synthetic DNA” as a way to mark a burglar with a unique DNA signature. Meanwhile, scientists at Erasmus University Medical Center in the Netherlands claim to be able to predict hair color using 13 markers in 11 genes. Previously, only red hair was predictable from DNA sequence. This investigative science needs further validation, but it could be useful, for example, in narrowing down a list of suspects with different hair colors, where DNA evidence has been recovered from a crime scene. And an interesting development was reported in Cardiff (UK), where bus drivers have suffered an unusually large number of personal attacks. The drivers are now being given spit kits, so that if someone spits on them, they can swab the saliva to assist in finding and prosecuting the spitter.

Continuing to Question the Reliability of Forensic DNA. DNA evidence is generally regarded as highly reliable, but lately research scientists have voiced skepticism about the degree of subjectivity sometimes required to make a determination as to when a match is found or when a defendant “cannot be excluded” on the basis of DNA evidence. A 2010 study showed that samples containing DNA from two or more unknown people present special challenges to forensic labs and force the analysts to make some judgment calls. The researchers sent a real gang rape sample to 17 different analysts and received back 3 different conclusions. Only one analyst arrived at the conclusion used to prosecute the one man who was convicted. A lack of national standards is partly to blame for the discrepancy. Ideally too, the analysts would be presented only with the DNA data, but many prosecutors provide the lab with additional information about the case, which may cause bias in the conclusions.

Another study reported a surprisingly high number of “coincidental matches” within state databases. The DNA profiling system is currently based on markers at 13 different variable spots in the human genome (“loci”). This report identified cases where all 13 markers matched in two people who were not identical twins. The researchers also discovered that partial match pairs with 9, 10, 11, or 12 loci in common were more frequent than expected. Both of the problems reported in these studies could be addressed by further examination of the DNA with sequencing or other more refined techniques, but even with the dropping costs of DNA sequencing, this would require tremendous financial investment. It would also increase the risk of exposing medically relevant genetic information, a problem largely avoided by current forensic analysis.

Where to Next for Forensic DNA? In light of these new developments and continuing questions regarding the use of forensic DNA tools and techniques, it is important to highlight one of the oldest and most successful applications of forensic DNA: the Innocence Project. Since its inception, the Innocence Project has used forensic DNA techniques to exonerate over 250 wrongly convicted people in the United States. The Innocence Project has expanded to an international effort, with the United Kingdom’s branch nearing its first exoneration (although not on the basis of DNA evidence), and advancing DNA sampling and analysis technology promises to drive further expansion.

When it comes to forensic DNA, the debate boils down to the same question as in many other contemporary debates, including TSA security searches, wiretapping, etc.: what price (both in financial and privacy terms) is society willing to pay in exchange for additional levels of safety? If events of just the past few months are any indication, this is a question that will continue to be thrust in front of both lawmakers and the voting public until it is more clearly resolved.

Allison Williams Dobson

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