By Mai Martinez

CHICAGO (CBS) – Investigators used genealogy websites to track down the suspect in the Golden State killings, the same websites that millions of people use to find out more about their ancestry.

Companies often require people taking DNA tests to agree to have their genetic profiles stored in a database. Those online databases provide users with possible family connections and relatives, but in the case of the Golden State Killer, it provided information to find the suspect.

“I was interested to see what kind of DNA was being used and how they did it,” said Dr. Karl Reich, a Chief Science Officer at Independent Forensics.

Dr. Karl Reich is a DNA expert and says he has a theory about how law enforcement was able to use DNA from a Golden State killer crime scene and the online databases to find a relative of the suspect, Joseph James DeAngelo.

“That sample must’ve been sent to one of the sites,” Dr. Reich explained. “And they ran what they do inside and then they submitted either a connection or family or lineages. [They had some sort of similarity, but] we don’t’ know how similar or how far apart.”

The DNA expert says it must have been enough to give law enforcement a list of possible connections which directed them to DeAngelo. Reich says police likely went through DeAngelo’s trash to get the DNA sample.

“You left a straw from your soda or you’ve gone and got a cup of coffee and used the lid, there’s enough, more than enough, DNA to give you a profile, and that profile can be compared to the profile they developed from any of the assaults,” explained Dr. Reich.

Investigators have not said which online sites were used in the investigation, but both ancestry.com and 23andMe said they weren’t involved in the case.

Dr. Reich told CBS 2 News that it’s possible law enforcement submitted the sample just like anyone can, and that’s how they gained access to the databases without having to get the companies directly involved in the investigation.