Police would solve more crimes if they expanded their use of DNA fingerprinting to test close relatives of known criminals, says a research report that raises novel and difficult civil liberties issues, reports the Washington Post. The strategy, already in growing use in Britain, is based on two central facts: Close relatives of criminals are more likely than others to break the law, and, because those individuals are related, their DNA “fingerprints” will be similar. That suggests that if police find a crime-scene specimen with a DNA pattern close to but not the same as that of a known lawbreaker, a relative of that known criminal may be the culprit.
In Britain, where rules governing the use of DNA for fighting crime are more permissive than in most U.S. states, the approach has helped solve several cases, said Frederick R. Bieber, a Harvard medical geneticist who led the new study with colleague David Lazer and Charles H. Brenner of the University of California at Berkeley. The analysis, published yesterday in the online edition of the journal Science, is the first to use sophisticated computer models to predict just how useful such “familial” searches may be. A 1999 U.S. Justice Department survey found that 46 percent of prison inmates had at least one sibling, parent, or child who had been incarcerated at some point. All states take DNA from all convicted felons, and many get specimens from a wide range of others. The new study calculated that U.S. police could increase their “cold hit” rate (the percentage of DNA searches that result in perfect matches) by 40 percent if they were to check the DNA patterns of criminals’ family members when searches generate near misses.