For decades, these rapes went unsolved. Today, a suspect is behind bars.

A Benicia man who worked for 25 years at the University of California, Berkeley was arrested Thursday in Berkeley on suspicion of sexually assaulting 10 women in at least six counties between 1991 and 2006.

Law enforcement agencies and district attorneys from the counties announced the arrest of Roy Charles Waller, 58, allegedly the so-called Nor-Cal Rapist, at a news conference in Sacramento Friday morning.

DNA evidence linked Waller to a sexual assault that occurred in October 2006 in Sacramento, the Sacramento Police Department said in a news release.

Waller is scheduled to be arraigned Monday afternoon in Sacramento County Superior Court on 12 felony charges, some of which carry life prison terms, Sacramento County District Attorney Anne Marie Schubert said. He is in main Sacramento County Jail on no bail status.

The alleged rapes occurred in Sonoma, Solano, Contra Costa, Yolo, Butte and Sacramento counties. The first assaults happened in Rohnert Park in 1991 and in Sonoma in 1992. The most recent was in Sacramento in 2006, law enforcement officials said at the new conference.

Waller entered homes late at night, overcame or bound women and committed repeated sexual assaults, law enforcement officials said. He ransacked homes and took some of the property or took the victims to an ATM machine to get cash, officials said.

Law enforcement officials described the 27-year investigation as complicated.

Schubert said:

“The answer has always been in the DNA.”