Reevaluating the Threshold Question in the wake of Carpenter and the path of the Golden State Killer
By Brady O’Bryan*
Between 1974 and 1986, a string of brutal rapes and murders terrorized California.1 Though the crimes spread across ten different counties, their similarities led law enforcement to suspect that the perpetrator was a single manâ"The Golden State Killer" ("GSK").2 Until recently, efforts to identify the sadistic criminal had produced little more than rough sketches.3 Then, Paul Holes, a crafty investigator and DNA expert, wondered if the recent rise of commercial genealogy databases could provide the spark in a case that had run four-decades cold.4 As it turns out, law enforcement had long held a sample of GSK’s DNA collected from a crime scene.5 However, because the sample did not match any profile in the government’s DNA databases, it was all but useless.6 Until now. In a stroke of genius, Holes sent in a sample of the DNA7 to GEDmatch.8 The open-source ancestry site established a connection to GSK’s great-great-great grandfather.9 From this point, investigators were able to craft a sprawling family tree that narrowed their search.10 That was all they needed to produce the case’s biggest break in 40 yearsâGSK had a name.
The investigation tactic has since inspired other law enforcement offices to do their own ancestry sleuthing, and understandably so.11 Until now, DNA identification was limited because law enforcement’s database contained a small subset of the populationâlargely convicted felons.12 Even with this limit, DNA identification is ubiquitous and a powerful tool for detectives and prosecutors bringing criminals to justice.13 Recent reporting indicates that the pool of profiles submitted to online genealogy services is large enough to identify sixty percent of white Americans; and that number is expected to rapidly increase in the coming years.14 It is no surprise that law enforcement wants to augment its existing database with open-source ancestry sites and someday gain the ability to identify every person in the country by DNA sample.15 It is the kind of power J. Edgar Hoover could only have dreamt of while painstakingly cataloging his fingerprint database.