OAKLAND -- The trial of a computer programmer accused of killing his estranged wife opened with a prosecutor attacking the notion that the woman, whose body has never been found, may yet be alive.

Nina Reiser was devoted to her two children, aged 6 and 5 when she disappeared, and wouldn't have forsaken them to the uncertainty of foster care, prosecutor Paul Hora said as he began his opening statement Tuesday.

"She would have never, ever, abandoned those kids," Hora said, his normally soft voice rising in emphasis. "Impossible."

Nina Reiser, 31, vanished in September 2006, after dropping her son and daughter off at the home of her estranged husband, Hans Reiser.

Hans says he is innocent of the crime and his attorneys have said it's not clear that Nina is even dead.

"I don't know where she is. I don't know what happened to her when she disappeared or where she went," defense attorney William Du Bois said outside the courtroom Tuesday.

Investigators say they found small amounts of blood matching Nina's DNA at Hans' home. They also reported finding blood in his car, which was missing the front passenger seat when police found it.

"You're going to know without a doubt, something happened to Nina," Hora said. "Something terrible happened to Nina."

Hora began by telling jurors he wanted to introduce them to someone they wouldn't be hearing from, Nina.

He flashed snapshots of a smiling Nina and her children on a flat-screen TV hanging on the courtroom wall and made his remarks flanked by a large portrait of the woman, elegant in black, holding her infant son.

Hans, wearing a charcoal gray suit, sat at the defense table, frequently leaning in to whisper to his attorney as Hora spoke.

Nina, Russian by birth, was a trained doctor when Hans, a prominent computer programmer, met her while doing business in Russia. They married in 1999, but by 2004 the marriage had fallen apart, Hora said.

The prosecutor acknowledged that during one of Hans' frequent absences on business, Nina had an affair with his best friend.

"There's not any way to sugarcoat it," he said.

Nina filed for divorce, beginning long and highly contentious proceedings, said Hora. The couple fought over custody, the health and education of their young son and money. Things were so tense between them that at one point a judge ordered them to pick up and drop off the children in a neutral setting.

Du Bois, who may address jurors Wednesday, said during a break that Hora's opening was "reaching."

"The harder they reach, the more it's indicative of the weakness of their case," Du Bois said. He took issue with the prosecution's view of Nina, saying she left the children on two occasions, once for two months, and describing her as a "high-liver" and very image-conscious.

But in his courtroom remarks, Hora painted quite a different picture, saying he would present testimony from people who knew both Reisers.

"She would have never, ever let those kids suffer, not knowing where she was," Hora said. "She would have never been that cruel."