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Thanks to genetic genealogy, a Northern California woman was arrested in the killing of her newborn baby boy who was found dead 32 years ago, officials said.

The Alameda County Sheriff’s Office says 52-year-old Lesa Lopez admitted to investigators she was the mother of the baby and implicated herself in the crime.

This July 23, 2020 booking photo provided by the Alameda County Sheriff's Office shows Lesa Lopez, 52. The California woman was arrested for allegedly killing her newborn baby boy in the San Francisco Bay Area 32 years ago in a case that was solved decades later thanks to genetic genealogy, authorities said Monday, Aug. 3, 2020. (Alameda County Sheriff's Office via AP)
This July 23, 2020 booking photo provided by the Alameda County Sheriff’s Office shows Lesa Lopez, 52. (Alameda County Sheriff’s Office via AP)

Two young boys were walking in Castro Valley in 1988 when they found the lifeless newborn inside a bag at the top of an embankment of a creek near Madison Avenue. 

An autopsy ruled the death a homicide, finding that the baby was alive at birth.

Investigators scoured local hospitals in an effort to track down the child’s mother, but they were unsuccessful. And while they did receive tips from the public, detectives found no viable leads, the Sheriff’s Office said.

About 200 people attended a funeral for the baby, who was being referred to as “Baby John Doe,” in July 1988. At the service, church leaders named the newborn Richard Jayson Terrance Rein.

The case went cold for 17 years, until 2005, when DNA evidence was identified, linking the child to a female. But the DNA didn’t match any identities available in the system, authorities said.

More than a decade later, armed with advancements in DNA technology, cold case investigators reopened the case in 2019 and used a private DNA lab, and help from the FBI, to search through publicly available genealogy sites.

“Nearly a year later, in June of 2020, after conducting extensive genealogy research, physical surveillance, and through DNA analysis of surreptitiously obtained discarded trash, investigators identified DNA evidence linking 52-year-old Lesa Lopez of Salida, California, to the DNA evidence found at the crime scene,” the Sheriff’s Office said.

Lopez was found and arrested at her home on July 23.

Sheriff’s officials said the woman told them she was 20 years old at the time and had hid the pregnancy from her friends and family.

It wasn’t immediately known if she has an attorney who can speak on her behalf.