Familial DNA searching, though still controversial, is being seriously considered for forensic use.To search or not to search, that is the question. And despite some vocal criticisms and concerns regarding the practice of familial DNA searching, increasingly the answer is “yes.” What that means for the forensic community in its entirety remains to be seen, but for states that have moved forward with familial searching programs, protocols continue to be refined.

Forensic familial DNA searching for investigative purposes has made headlines in recent years, particularly with the capture and prosecution of the high-profile “Grim Sleeper” serial killer suspect in California. In this case, a search of California’s DNA database revealed that the DNA from a young man who had recently been arrested in the Los Angeles area partially matched samples taken from Grim Sleeper crime scenes. The match strongly indicated that this man was either the child or parent of the person committing these crimes. From that lead, detectives narrowed the investigation to the arrestee’s father, tested a discarded slice of pizza the suspect left at public food court, and ultimately arrested Lonnie David Franklin Jr. as the Grim Sleeper.

Some experts suggest familial searching could increase the yield of investigative leads by up to 40%, helping law enforcement solve more crimes. The practice is used in the United Kingdom, California, and Colorado, was recently adopted in Virginia, and is under consideration in Pennsylvania. Florida has been informally using the practice for some years, and other states are considering adding the technique to their crime-solving arsenal.

While familial searching may be effective given a particular set of circumstances, many questions remain. Critics argue that the practice puts unsuspecting and law-abiding citizens under genetic surveillance and violates a constitutional right to privacy that shouldn’t be surrendered just because a relative has given up his rights by committing a crime. And, because the current U.S. databases have a disproportionate number of African American and Hispanic samples, others argue the practice is a new form of racial profiling.

One of the most prominent opponents of familial searching is Stephen Mercer, chief attorney for the Forensics Division of the Maryland Office of the Public Defender. Mercer was instrumental in helping Maryland categorically ban familial searches. Mercer also testified before the District of Columbia city council against familial searches, and the council amended its DNA collection statute to ban the practice. So far, D.C. and Maryland are the only states to take this approach. “In Maryland, we identified a trend toward continued expansion of the database that was disturbing,” said Mercer. “It heralded an era of unwanted genetic surveillance that just wasn’t reasonable. Why should I forfeit my rights just because a family member chooses to commit a crime? Is that reasonable? Genetic surveillance of a group that is largely defined by race is the harm in a democratic society.”

Mercer says the D.C. ban speaks volumes because rather than operating its own database as all 50 states do, D.C. samples are entered directly into the National DNA Index System (NDIS) database.

Not everyone agrees, however.

David Kaye, law professor at Penn State University, has been studying genetics in the law and the use of science and statistics in litigation for almost his entire career. “I don’t think there is a convincing constitutional objection to locating suspects in this fashion, at least not if it’s done carefully, with suitable science behind it, and avoiding unnecessary disclosures of sensitive genetic information about individuals,” he said.

For Kaye, narrowly defined regulations and proper investigative training is the key to success. “I think familial searching and the resulting investigations should be done pursuant to regulations that minimize hassling people and revealing things about their relatives that don’t have to be revealed. There can be sensitive information about family relationships. I wouldn’t want police to be heavy handed about this. I stand with the group that says this is appropriate if done sensitively. On the other hand, I’m on the end of the spectrum that would favor this more routinely than some of my colleagues.”

Kaye agrees that the disparate impact on African Americans and Hispanics is a valid concern. “There are a relatively large number of minorities in the database. Kinship searching increases the sheer number of cases in which the members of some groups are more likely to be caught if they commit a crime. But if you have a technique that works, even if it doesn’t work as broadly as you’d like, it may still be worth doing. As far as the constitution is concerned, disparate impact is simply not a violation of the equal protection clause. It is an issue to be weighed at a policy level, but it is not a convincing ultimate argument against kinship searching,” said Kaye.

For most forensic professionals, the science is the primary concern. Brad Jenkins, forensic biology program manager for the Virginia Department of Forensic Science, said, “DNA is blind to race. You have a DNA type and you’re trying to find a particular match for that type.” For Jenkins, that part is simple. The rest comes down to policy, which involves weighing the societal benefit against the potential harm given an imperfect system. “My recommendation to states considering familial searching would be to divide it into two processes. Have your crime lab work on the scientific process, the casework and computer program, which is all very straightforward. And then have your legal staff or attorney general’s office work on the legal aspects and determine what legislation, if any, is required to support the process and ensure it is implemented correctly within the law,” he said.

The Grim Sleeper was a textbook case of how familial search techniques work to help investigators find new leads in cases where the trail has gone cold. In California, fairly restrictive laws surrounding familial searching demand this. States new to the process, like Virginia, have followed suit, limiting through legislative or administrative measures the type of cases and situations that are allowed to use the practice. This is due to both ethical reasons, to limit familial searches to the appropriate cases, and the availability of resources. A familial DNA search is far more time and labor intensive than a traditional DNA search seeking an identical match. When processing evidence, a traditional database search may result in one match to a single individual. A familial search, however, may result in many matches to many different individuals. These samples are then subjected to additional DNA “lineage” testing to determine if the individuals are potentially related to the donor of the crime scene evidence. In a database the size of Virginia’s containing approximately 330,000 samples, a single crime scene evidence sample subjected to a familial search can result in the additional genetic analysis of about 100 samples to determine potential relation to the crime scene sample donor. This additional genetic analysis is completed prior to reporting results to law enforcement. As the number of individuals in a database increases, the number of samples requiring this additional genetic analysis will also increase.

Despite the resources required, many believe the practice will become increasingly common. “Given recent history, I think that more states will pass laws or adopt regulations permitting the practice. I think these will ultimately be challenged in court, but I think courts will uphold the practice,” said Kaye.

Kaye says the real question for the future is policy. California’s law is pretty restrictive as it stands, using familial searches as a last resort measure when all other options have been exhausted. But as people become more comfortable, it is possible the practice could be done as an upfront, proactive measure.

“Instead of waiting until a case runs into a blank wall, we could design a database that has more information in it right away, so that whenever there is search on a crime scene sample it operates in stages. First, it asks if there is a match, period. If not, it searches for a close match indicative of a relative. This could be done by putting additional loci into the records,” said Kaye.

If databases were expanded to include Y-STRs—the genetic markers fathers pass down to their sons that help identify male relatives in familial searches—this is a distinct possibility. This would lead to more possible suspects, along with additional controversy. But other hurdles exist, too. As it stands, investigative information about suspects, like demographics and geographic information, is held in systems separate from the current DNA database systems. This makes doing the required investigative work more difficult and time consuming.

Today, familial searches are used relatively rarely. Though official numbers are hard to come by, informal reporting reveals useful investigative matches are generally found in a handful of cases. For instance, the Virginia crime lab, new to familial searching this year, anticipates it could process approximately 10 to 12 familial searches annually. Even the United Kingdom, which has allowed familial searching since 2002, has only processed about 200 samples with a 20% or less success rate for familial matches according to various reports as of May 2011. Like any DNA matching process, oftentimes no match is found.

But that relative rarity doesn’t mean that accidental matches don’t happen. According to Kaye, there have been instances where someone working with a database on a match will notice a situation that does suggest a relative. In a state without regulation, the issue gets sticky. At present, there is no clear practice—some get reported, others do not. “I say let’s have clear policies and tell people what to do and try to write the best policies. We can disagree on what the best policies are, but it is important to deal with the situation as it exists. That’s why I favor addressing this legislatively or at least administratively,” said Kaye.

Adding a measure of clarity would also inform training, something that is already critical for those states adopting familial searches. Said Jenkins, “Familial searching doesn’t change forensic fieldwork, we’re still collecting evidence under standard procedures. However, educating all stakeholders in the process is a big and important change. Educating detectives, attorneys, and judges about the technique, its availability and limitations, and proper procedures is more of a challenge than collecting evidence at the crime scene.”

David Kaye is a Distinguished Professor of Law, Weiss Family Scholar, and Forensic Science Program Graduate Faculty Member at Penn State University. He is also the author of “The Double Helix and the Law of Evidence: A Scientific and Legal History.”

Stephen Mercer is the Chief Attorney for the Maryland Office of Public Defender Forensics Division and Adjunct Faculty at the David A. Clark School of Law for Forensic Scientific Evidence.

Brad Jenkins is the Biology Program Manager for the Virginia Department of Forensic Science.

A workshop featuring an international panel of law enforcement, legal, and forensic experts will discuss the issues surrounding familial searching from 8:30am to 5pm, Monday, October 3, 2011, during the 22nd International Symposium on Human Identification (ISHI) in Washington D.C. Visit for more details.