DNA: Between crime busting and privacy

India has a proposal that would make it mandatory for anybody making a police complaint to provide a DNA sample

The case of the Golden State Killer is an astounding thriller. The California police solved a string of horrific crimes and identified the perpetrator by means of DNA analysis and matching. Between 1977 and 1986, a rapist-killer stalked California, attacking people across multiple small towns in and around the state capital of Sacramento. He committed at least 50 rapes and 100-odd burglaries and murdered at least 12 people. 

The crimes were conclusively linked together by DNA evidence as well as by the common modus operandi. The DNA linkages were only possible around the year 2000 although it was strongly suspected that the same person was responsible, due to the similarity of methods. 

The so-called Golden State Killer, (also known as the Night Stalker and the East Bay Rapist) attacked single women as well as couples. He would break-in at night, tie up the couples, rape the women, and steal. Sometimes he would just leave afterwards. On other occasions, he would bludgeon them to death. 

He made taunting follow-up phone calls to the victims and the police. Survivors described a youngish, athletic man of medium height. The phone calls continued sporadically until 2001, at least 15 years after the last known case. In 2016, the FBI announced a reward of $50,000. 

The case was finally broken this week, when the Sacramento police announced the arrest of Joseph James DeAngelo, a 72-year-old retiree living peacefully with his family in a Sacramento suburb. DeAngelo is a former police officer. He served in the US Navy in Vietnam before spending many years in the police forces of two small towns in the Sacramento area. His wife is a lawyer, and one of his three daughters is a doctor. He was dismissed from the police for shoplifting. After that, DeAngelo worked at a supermarket’s logistics centre, repairing and maintaining trucks.  

The first use of DNA in criminal cases started only in 1987, a year or so after the Golden State Killer apparently stopped operating. Using techniques that were not available at that time, the police eventually harvested DNA from the crime scenes in the 2000s. Then, they ran that DNA through genealogical DNA-testing sites which use Do It Yourself (DIY) methods. 

There are now many such DNA testing sites. Clients upload their own DNA samples, which are then tested for family ties to other people in the database. The more popular websites have now digitised and stored millions of DNA samples. 

These sites use a method of sampling for unusual DNA strings and searching the database for similar unusual strings to find possible family matches. Many sites also do tests for hereditary conditions and propensity to diabetes, heart disease, etc. 

The police uploaded the DNA samples to one or more of these sites. They are being understandably cagey about the exact method followed — the website, or sites, are unknown. 

It is even possible that, instead of being upfront and demanding that the sites cooperate with law enforcement, the police signed up as a paying customer and uploaded the DNA. 

Some distant family matches came up. At that stage, the authorities could narrow the search by looking at the probable age of the killer, the known locations of individuals during the period when the crimes were committed, and so on. Finally, the police used “discarded DNA” gleaned from DeAngelo’s house to nail him.

It’s a fantastic story. At one level, it makes a striking case for the use of DNA in solving crimes, including cold cases from 40 years ago. At another level, there are disturbing privacy issues. Did these websites voluntarily give away client-data? Is it possible to sign up and get to know strangers one may be related to?  When do the police take DNA samples? How long do samples stay on record? How easy is it to fake a digitised DNA record? 

India has plenty of DIY DNA sites doing genealogical testing. India also has a proposal that would make it mandatory for anybody making a police complaint to provide a DNA sample. India also doesn’t have a privacy law. Given this case, and the current state of Indian policing, the possibilities are disturbing.

Twitter: @devangshudatta