It started out as an afternoon of sun and fun on a personal watercraft in San Pablo Bay, until Corbin and Jennifer Easterling ran into trouble and wound up clinging all night to their broken-down, barely floating machine.

Corbin Easterling says that when he woke up, his wife was dead. Authorities say he killed her, and that autopsy results show he covered her mouth and nose and held her head underwater.

Opening statements in his murder trial are planned this week.

Easterling, 36, steadfastly maintains his innocence. He says that while he slept, his wife of five months and the mother of their daughter, now 2, died of hypothermia in the cold water.

"I was passed out. When I woke up, my wife was gone. She'd passed on. There was nothing I could do about it," he said during a recent telephone interview with The Associated Press from his Sonoma County jail cell. "It was an accident."

Easterling told police he and his 35-year-old wife hit the water around 11 a.m. on Oct. 11, 2004, after stopping for drinks at a bar. They wore life vests, he said, and spent the afternoon cruising the bay about 20 miles (32 kilometers) northeast of San Francisco on their WaveRunner.

They were headed home when it overheated and caught fire, Easterling said. They were left clinging to the side of the partially submerged machine for hours.

Jennifer Easterling called the emergency dispatcher on her cell phone but got cut off, he said. They also called her father and asked him to send help, Easterling said, but Richard Jevarian did not call authorities until the next morning.

"I lost my wife. I had no time to mourn her. I was accused of harming her," he said. "If her parents would've called the Coast Guard like I told him to, we would've been OK."

Jevarian maintains that he did not believe the couple were in any real trouble. He says his daughter frequently blew her problems out of proportion and that he did not get worried until the next morning when he could not reach her. That is when he called the Coast Guard, which picked up Easterling and his wife's body.

A forensic pathologist testified in April 2005 that bruises on Jennifer Easterling's body and face, cuts inside her mouth and water in her lungs were among the factors that helped him reach the conclusion she was murdered.

"What caused her to die was being held under water," Dr. Gregory Rieber testified. "The hand over the mouth left injuries that indicate that there was a component of suffocation before she died."

A hypothermia expert hired by the Sonoma County district attorney's office disputed Rieber's findings, saying "the victim could have drowned as a result of hypothermia-induced unconsciousness."

However, prosecutor Alexander "Bud" McMahon said in a July 2005 note to his boss that the expert, Dr. Alan Steinman, agreed the prosecution's theory "is probably the correct one."

Both sides later agreed the water was likely colder than they originally thought. When a defense investigator re-interviewed Rieber in March 2006, he said that "certainly makes a drowning under accidental circumstances a lot more likely," according to a letter from the investigator to the Sonoma County sheriff obtained by the AP.

Easterling's lawyer, Marie Case, did not return several calls seeking comment.

Prosecutor Spencer Brady refused to answer specific questions, citing concerns about tainting potential jurors.

"We're ready to go," he said. "We believe the evidence is sufficient for a Sonoma County jury to return a verdict of guilty."