The prime suspect in the fatal stabbing of a 14-year-old Castro Valley girl has died in an Oregon prison, officials said Monday.

Sebastian Alexander Shaw, 53, died of an undisclosed cause Sunday in the Oregon State Penitentiary, where he was serving three life sentences for murder. An autopsy will be conducted, prison officials said.

In 2006, Alameda County investigators identified Shaw as the main suspect in the 1994 murder of Jenny Lin, who was killed by an intruder in her home. He had been in prison since 2000 and was never arrested or charged for the girl’s killing.

In addition to the three murders for which he was convicted, Shaw allegedly told police he had committed 10 to 12 more, including an unspecified California case.

In August 1994, Shaw, then 26, had been arrested in Portland by police who found him in a car reported stolen in San Ramon in early June — the week after Jenny’s death.

Police found in the car a handgun, two rifles, knives and what they called a “murder kit” — ski mask, surgical gloves, duct tape, binoculars and handcuffs. Prosecutors in California declined to charge him with the car theft, and he was released.

DNA evidence led to Shaw’s arrest in 1998 in two Portland cases: the killings in 1992 of a young couple in their trailer home and the rape of an 18-year-old woman in 1995. He pleaded guilty to those cases in 2000 and was sentenced to two life terms.

Jenny Lin. (Family photo) 

The third life term was added for a later conviction in the 1991 slaying of a quadriplegic man in his Portland home.

Shaw reportedly refused to disclose details of his other crimes unless he had a guarantee he would not face the death penalty. Such a deal was never reached. Jenny Lin’s murder remains officially unsolved.

Jenny was an eighth-grader at Canyon Middle School, a straight-A student and talented musician.

On the afternoon of May 27, 1994, the Friday of Memorial Day weekend, she was alone in her family’s house in the Palomares Hills neighborhood after returning from school. She spoke to a friend on the phone around 5:15 p.m.

When her father got home that evening, he found the girl’s body in an upstairs bathroom. She was naked; investigators believe her killer intended to sexually assault her but was scared off.

Her family started a foundation in her name that promotes child safety and music education. It remembers her life with a  memorial event each year.