https://amp.cnn.com/cnn/2018/06/02/us/golden-state-killer-unsealed-warrants/index.html
When the suspected Golden State Killer drove into a Hobby Lobby parking lot in April, investigators were waiting nearby. As he walked into the craft store, it gave them a perfect chance to collect a secret DNA sample.
Police swabbed the driver's side handle of [the suspect's] car, according to arrest and search warrants released Friday.
Authorities sent it for testing and matched it to semen recovered at some of the Golden State Killer's crime scenes, the arrest warrant said.
[...] The stop at the Hobby Lobby was just one of several ways investigators used to zero in on a suspect. Earlier this year, police tracked him down by comparing genetic profiles from genealogy websites to crime scene DNA, according to investigators.
On April 23, a day before his arrest, police say they collected multiple samples from a trash can outside DeAngelo's home in Citrus Heights, a town 16 miles northeast of Sacramento. They had watched the home for three days, the warrant said.
Previously: DNA From Genealogy Site Led to Capture of Golden State Killer Suspect
GEDmatch: "What If It Was Called Police Genealogy?"
(Score: 3, Informative) by frojack on Monday June 04 2018, @06:34PM
Exactly.
But they had a complete semen DNA sample from back in the day. They had already been able to reduce the pool to specific racial profile, as well as other genetic markers. They weren't interested in huge swaths of the population by that point. So they submitted it to the DNA service INTENTIONALLY to gain a familial match, which is what this service specialized in. This was the only real "Hail Mary" play in the whole investigation.
Once you know it is a relative of a particular person (himself too young to be involved) you work outward from there.
Standard police work. Forget the Females, Eliminate the males one by one, wrong age, not present at the time, DNA already in (one of the) systems, already dead, already in custody, bats for the other team.
By this time you've probably got it down to less than 10. (swag).
Then start collecting DNA. Maybe you just ASK those you least suspect.
Maybe you dig through trash, watch for publicly discarded items.
I'd guess by that time you are down to two or three people.
There is a LOT of this case that is just dogged police work.
No, you are mistaken. I've always had this sig.