MARTINEZ, Calif. -- A capital trial began Monday for an alleged serial rapist and killer accused of kidnapping, raping and murdering a 40-year-old Lafayette mother on a popular jogging trail 30 years ago.

Darryl Kemp, now 72, sat in a wheelchair in Contra Costa County Superior Court in Martinez. He was wearing dark glasses and had his gray hair pulled back in a ponytail.

Kemp has been charged with murdering Armida Wiltsey on Nov. 14, 1978. He is also facing the special circumstances allegations of murdering Wiltsey in the course of a rape and murdering her in the course of a kidnapping, charges that could bring him the death penalty.

David Headley, one of Kemp's two attorneys, urged jurors to remain analytical as they listened to what is expected to be emotionally upsetting testimony from Wiltsey's family and from Kemp's surviving victims.

Headley did not dispute that his client was a serial rapist and said he was guilty of "probably a dozen rapes," including some in which he broke into women's homes to rape them, but argued that Kemp never intended to kill his victims.

Over the years, he developed a clear pattern of behavior, Headley said. He would knock his victims unconscious, rape and sodomize them and then, when they woke up, he would talk to them, asking them embarrassing questions.

On the day she was killed, Wiltsey kissed her husband goodbye as he headed off on a business trip and then dropped her 10-year-old son off at school, Prosecutor Mark Peterson said.

At some point that day, she went for her regular jog on a paved trail that goes around the Lafayette reservoir.

Nobody knew she was missing until she failed to pick up her son from school that afternoon, Peterson said.

According to Peterson, the boy, Jeffrey Wiltsey, waited for his mother for half an hour, watching as all the other children were picked up. Then, not knowing what else to do, the boy walked about a mile to the family's home, where he found his babysitter.

By nightfall, when Wiltsey still hadn't come home, her son and his babysitter went to their neighbor's house and told them Wiltsey was missing. The neighbors called the sheriff's office, which had jurisdiction over the reservoir, Peterson said.

Deputies found Wiltsey's car parked on Mt. Diablo Boulevard near the reservoir and started searching, using a helicopter and eventually a bloodhound that led deputies to Wiltsey's half-naked body.

She was found lying in the "fetal position" in the brush about 65 feet from the trail, Peterson said. Her was body covered with cuts and scrapes. She also had injuries to her mouth, neck and vaginal area and ligature marks on her wrists from being tied up, Peterson said.

He said she had either been strangled or suffocated.

The crime remained unsolved for 25 years until a criminalist in the Contra Costa County crime lab decided to re-open the investigation and was able to match DNA taken from under Wiltsey's fingernails to Kemp's DNA, Peterson said.

"He kidnapped her and he sexually assaulted her and he murdered her. The evidence is overwhelming," Peterson said.

Kemp was in prison in Texas serving a sentence for a 1983 rape of a woman in Austin, Texas when he was charged with Wiltsey's murder.

In 1959, 19 years before Wiltsey's murder, Kemp was convicted of the June 10, 1957 rape and murder of Marjorie Hipperson in Los Angeles. At that time, he was also convicted of raping a second woman in a Los Angeles park May 10, 1959 and of kidnapping and raping a third woman on July 15, 1959, also in Los Angeles.

Kemp was sentenced to death for Hipperson's murder, but his sentence was commuted to life in prison after the death penalty was declared unconstitutional in the mid-1970s.

While in prison, Kemp befriended a Pleasant Hill woman through an inmate pen pal program run by Diablo Valley College. He was paroled to Contra Costa County to live with his pen pal on July 23, 1978, just four months before Wiltsey's murder.

The woman kicked him out of her house after she allegedly caught him fondling her daughter, Peterson said.

On Nov. 30, 1978, just over two weeks after Wiltsey was killed, a Walnut Creek man saw Kemp standing outside his neighbor's window at about 3 a.m. masturbating. The man called police and Kemp was later convicted of prowling.

Kemp then moved to Texas, where he was convicted of the 1983 rape.

"Darryl Kemp, ladies and gentlemen, is a serial rapist. Darryl Kemp is a serial murderer," Peterson said.

Headley said Kemp's method was "reckless" but "he's not intentionally killing them and that's a big difference."

"He doesn't take pleasure in killing them," Headley said. "He takes pleasure in raping them and then talking to them afterwards."