So, the “Golden Gate killer” has been caught, after forty years. Good news, to be sure, and it’s exciting to hear of the police using modern data systems creatively:
Investigators used DNA from crime scenes that had been stored all these years and plugged the genetic profile of the suspected assailant into an online genealogy database. One such service, GEDmatch, said in a statement on Friday that law enforcement officials had used its database to crack the case. Officers found distant relatives of Mr. DeAngelo’s and, despite his years of eluding the authorities, traced their DNA to his front door.
And yet… This is just another example of how all traditional notions of privacy are crumbling in the face of the twin assaults from information technology and networks. We see this in the way Facebook generates shadow profiles with information provided by your friends and acquaintances, even if you’ve never had a Facebook account. It doesn’t matter how cautious you are about protecting your own data: As long as you are connected to other people, quite a lot can be inferred about you from your network connections, or assembled from bits that you share with people to whom you are connected.
Nowhere is this more true than with genetic data. When DNA identification started being used by police, civil-liberties and privacy activists in many countries forced stringent restrictions on whose DNA could be collected, and under what circumstances it could be kept and catalogued. But now, effectively, everyone’s genome is public. It was noticed a few years back that it was possible to identify (or de-anonymize) participants in the Personal Genome Project, by drawing on patterns of information in their phenotypes. Here’s a more recent discussion of the issue. But those people had knowingly allowed their genotypes to be recorded and made publicly available. In the Golden Gate Killer case we see that random samples of genetic material can be attributed to individuals purely based on their biological links to other people who volunteered to be genotyped.
The next step will be, presumably, “shadow genetic profiles”: A company like GEDmatch — or the FBI — could generate imputed genetic profiles for anyone in the population, based solely on knowledge of their relationships to other people in their database, whether voluntarily (for the private company) or compulsorily (FBI).