A map marking where a series of rapes in Northern California occurred starting in 1991 next to a photo of suspect Roy Charles Waller, 58. (AP Photo/Rich Pedroncelli)

Authorities in California said they arrested a man they suspect is a serial sexual offender who committed a string of horrific crimes over 15 years, earning the name the “NorCal rapist.” They attributed the breakthrough in the case to DNA, drawing parallels to the Golden State Killer case that made headlines earlier this year.

Officials, including Sacramento County District Attorney Anne Marie Schubert and the city’s police chief, Daniel Hahn, said at a news conference Friday that they had arrested Roy Charles Waller, 58, and charged him with 12 counts of forcible sexual assault, according to the Sacramento Bee. He is currently being held without bail before his arraignment on Monday.

The NorCal rapist victimized at least 10 women in six northern California counties over a period of 15 years starting in 1991, Schubert said.

Detective Avis Beery, who has been working on the case for more than 12 years, described the NorCal rapist’s methodology: He would enter houses, usually when the victims would be asleep, then overcome and bind the women before sexually assaulting them. Sometimes he’d kidnap them and take them to an ATM to get money out of their accounts; other time’s he’d steal from their homes, Beery said. Officials said he targeted Asian women, local news outlets reported.

Waller was arrested Thursday in the city of Berkeley, where he worked at the University of California’s environment, health and safety office as a “safety specialist,” according to its website. Waller has been married and had the same job for about 25 years, officials said Thursday. None of the suspected rapes occurred in Alameda County, where the university is located.

“We were shocked today to learn that a campus employee was arrested in connection with a series of rapes that occurred over more than a decade ago in several Northern California communities,” spokesman Roqua Montez told the San Francisco Chronicle. According to the university police and the Sacramento Police Department “there is no indication that any crimes occurred within the campus community,” he said. However, the campus police will review any open sexual assault cases to determine if any might be related, he added.

Waller’s duties included “managing programs to help ensure safety and training regarding the use of equipment and machinery including forklifts, aerial lifts, respirators” Montez said.

The first attack was in 1991, when a woman was raped in Rohnert Park. Then another attack in Vallejo, and another in Martinez on Halloween in 1996, the Chronicle reported. In that case, the man wore a skeleton mask then called the victim at work less than a month later to apologize, the Chronicle reported.

Schubert said the unifying thread in the cases was the suspect’s DNA.

“For 27 years there has been one common thread, his DNA,” she said. “I have often said in my career that DNA is the silent witness to the truth.”

The arrest was reminiscent of that of Joseph James DeAngelo, who was arrested in April on the suspicion that he was the so-called “Golden State Killer,” who was wanted for raping dozens of women and killing at least 12 people in a bloody swath of crime that spanned decades in the state.

Like DeAngelo, Waller was arrested after police searched the genealogy site GEDmatch for leads. In DeAngelo’s case, officials did what’s called a familial DNA search of GEDmatch, in which they sought to find someone who was closely genetically related to him, and worked backward to find a suspect. Familial DNA searching, particularly as it relates to government-run DNA databases, has come into wider use around the country, but it raises complicated questions about whether it means that the privacy rights of people are forfeited, in effect, by the decisions made by their relatives.

It was not immediately clear if police did a familial search in Waller’s case or found his profile in GEDmatch.

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