The most disturbing details about the Golden State Killer

From his first known crimes until his arrest in 2018, Joseph DeAngelo spent over 40 years at large. Yet the evidence was there, with common behavior patterns, shared territories, and DNA evidence. So why was he unknown before 2018?

For one thing, DeAngelo took advantage of his police training to leave no trace. He routinely wore gloves and a mask, which meant police couldn’t find fingerprints or get a good description of the victims. Moreover, the killings seem to have stopped in 1986, when news of the first murder case solved by DNA evidence came to light. Perhaps DeAngelo, suspicious of new investigative techniques, was finally pressured to step away from his decades-long criminal career.

Then there was the problem of inconsistent communication between law enforcement agencies, which made connecting the dots even more difficult. It wasn’t until retired police investigator Paul Holes combed through genetic databases that the picture became clearer. Using a DNA sample taken from the crime scene at the home of Charlene and Lyman Smith in 1980, Holes and his colleagues found distant relatives of the attacker in the GEDmatch database, using a process now commonly known as “genetic genealogy.” Through careful genealogical research, investigators were eventually able to track down DeAngelo through these relatives. After tracking him and secretly collecting DNA samples from a handkerchief and a car door, they were able to confirm that he matched the crime scene material, and the Golden State Killer was finally arrested.