SANTA CRUZ -- A 50-year-old man convicted more than 20 years ago of sexually assaulting three women will be sent to a state mental hospital, a Santa Cruz County judge ruled this week.

Thomas August Towne was convicted of multiple charges in 1990 and was sentenced to 39 years in prison. During a hearing this week, it was determined there was sufficient cause to find Towne to be a sexually violent predator.

Under state law, prosecutors can seek civil confinement in a state mental hospital for convicted sex offenders determined to be sexually violent predators, a term meaning they have a diagnosed mental disorder that makes them at great risk of offending again. These proceedings typically begin about six months before an individual's scheduled release date.

A probable cause hearing must be held to determine whether a convicted sex offender can be confined as such. This is largely predicated on doctors' evaluations, and would typically then go to trial for the final decision. Towne, however, waived his right to a trial and will be committed to a state mental hospital, prosecutors said this week.

In 1989, Towne, then a bouncer in Capitola, sexually assaulted at least two massage therapists he found through newspaper classified ads. One of the masseuses testified at trial that Towne held her at knifepoint and forced her to perform a sex act.

The other testified that he forced her to strip at knifepoint, but she was able to scream for help into the telephone, scaring him off. Another masseuse was listening on the line at the time because the victim had a funny feeling about the customer, according to court records.

Towne checked himself into the mental health unit at Dominican Hospital after those attacks, but was later released. He then attacked and raped a woman in broad daylight on Opal Cliffs Beach, according to records.

The case was featured in an episode of CBS' "48 Hours" focused on victims and their rights.

Follow Sentinel reporter Jessica M. Pasko on Twitter at Twitter.com/jmpasko96