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How a son's DNA snared his father

A criminalist conducts DNA testing at a California lab.
A criminalist conducts DNA testing at a California lab.Calif. Attorney General's Office

Today's arrest in the "Grim Sleeper" serial-killing case demonstrates how the sins of the father can be found out through a son's DNA - and why the technique can be controversial. A 57-year-old one-time LAPD garage attendant named Lonnie Franklin Jr. was arrested in Los Angeles in connection with the string of 10 murders, committed between 1985 and 2007. The killer was nicknamed the "Grim Sleeper" because there was a 14-year break within that string, from 1988 to 2002. The case puts an unorthodox forensic tool known as familial DNA analysis at center stage. The method is specifically allowed only in two states - California and Colorado - and it's specifically banned in Maryland. New York is OK with using the method, but only if it's an "inadvertent" side effect of a more rigorous data search. The FBI currently has no firm policy on familial DNA matching but is willing to let states share their DNA data for use in the procedure. Now that familial DNA analysis has come up with a high-profile match, you'll probably be hearing much more about whether it should be used more widely. Not-quite-perfect match Why is the technique so controversial? It's because investigators look for not-quite-perfect matches between the DNA left behind at a crime scene and DNA markers taken from a wide sampling of people who may or may not have committed a crime themselves. The goal isn't necessarily to find the suspects, but rather the potential relatives of suspects. If there's a close match, investigators could focus their search on close relatives of the person who matched up - in hopes that the trail will lead to suspects who haven't left a DNA trail themselves. It's basically a crime-lab variant of the tests widely used to trace your genealogy, but these would be relatives you might not want to feature on your family tree. Familial DNA searches have been done in Britain for years, and California Attorney General Jerry Brown gave investigators the go-ahead to do the same in the Grim Sleeper case two years ago. A database search came up with a partial but significant match between DNA collected during the investigation and a routine sample taken from Franklin's son. Brown said the son was given a cheek swab after his conviction on a felony weapons charge. LA Weekly reported that the results of the DNA analysis "lit up like a Christmas tree." The investigators followed up by snagging DNA samples from Franklin himself. A relative of one of the Grim Sleeper victims who was briefed by police said that the sample was left on a restaurant cup, while the Los Angeles Times reported that the DNA was recovered from a discarded piece of pizza. The most likely scenario is that forensic sleuths tested the pizza, the cup and any other items that Franklin might have put to his lips while dining. District Attorney Steve Cooley told the Times that the arrest "shows the legitimacy" of using partial DNA matches and promised to provide more details at a Thursday news conference. If the arrest leads to a conviction, the feat will take forensic genetics to a whole new level. But it could raise a whole new crop of questions about genetic privacy as well. Lifetime genetic surveillance? In California, for example, the DNA samples are collected after every felony arrest, and may be retained even if the suspect later goes free. That has sparked a legal challenge from the American Civil Liberties Union. The ACLU noted that about a third of all those arrested for felonies in California are not convicted of any crime, and said that "thousands of innocent Californians will be subject to a lifetime of genetic surveillance because a single police officer suspected them of a crime." The ACLU also said the system could have a "huge racial impact" because a disproportionate number of people of color are already represented in California's criminal justice system, which serves as the main channel for the state's DNA sampling flow (at a rate of roughly 25,000 samples per month). The latest figures show that California has the biggest statewide DNA database in the country, with more than 1.5 million samples. ACLU calls it the third-biggest forensic DNA database in the world, behind the FBI's nationwide CODIS system (which includes the California samples) and Britain's national data bank. We're right in the midst of a massive crime-lab experiment in DNA collection. The federal government and all 50 states require those convicted of felonies to provide DNA samples, but California is just one of the 23 states that require DNA for felony arrests. Congress and several states, including New York and North Carolina, are currently talking about widening their DNA collection programs to cover arrests as well as convictions. Proponents of wider DNA testing say that such measures will prevent crime, save lives and provide more protection to the innocent. Opponents say that such measures will put more of a burden on the innocent, and that familial DNA analysis could turn even distant relatives into "genetic informants." I say that the Grim Sleeper case will increase the pressure on lawmakers to bulk up DNA databases across the country, and will lead to wider use of familial DNA as well. Is that a good thing, or a bad thing? What do you say? Weigh in on this issue by leaving a comment below. More on genetic sleuthing:

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