By Steve Large

SACRAMENTO (CBS13) — A terrifying mystery appears to be solved after investigators announced an arrest in a series of sexual assaults dating back nearly three decades.

Investigators say Roy Charles Waller is the man behind a series of sexual assaults spanning 15 years, starting in 1991. Waller was arrested as he arrived to work at UC Berkeley, where he has been employed for the past two decades.

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Waller’s former brother-in-law, who lives in Elverta, is in disbelief.

“I would say a happy-go-lucky kind of person, you know,” John Ferris said. “Good attitude, funny maybe.”

Neighbors at the Benicia home where he has lived with his wife are stunned.

“From a distance, he seemed normal, he was cutting down the trees and pruning,” Marsha Shigemotto said.

The NorCal Rapist’s terrifying M.O. was always the same—targeting young Asian women. One Sacramento victim came forward to share her story in 2006.

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“Every time when he gets away with it, he’ll just become bolder and do more harm,” she said.

Over the years, police released suspect sketches, videos from ATM, and home surveillance cameras.

“He would bind them, and then repeatedly sexually assault them,” Det. Avis Beery said.

Beery has worked on this case for a dozen years. DNA technology and the use of genealogy website “GEDMatch” connected the heinous crimes to Waller.

“I can’t say enough about the importance of that,” Beery said.

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An alleged secret life, exposed with high-tech tools –Investigators say this long-time public employee, Roy Charles Waller, is the NorCal Rapist.