With no body ever found, lawyers for the defendant, 44-year-old Hans Reiser, have suggested the children's mother, Nina Reiser, might be living secretly in her native Russia.

But in his closing argument, prosecutor Paul Hora said Nina Reiser would never have left her children to wonder night after night where she was.

"Can you think of anything more cruel?" Hora asked. "She wouldn't do that to those kids. It's vicious. It's cruel to do that to kids."

Nina Reiser, 31 at the time, hasn't been seen since dropping Rory, then-6, and Niorline, 5, off at Hans Reiser's house on Sept. 3, 2006.

Reiser, known in programming circles for his ReiserFS computer file system, says he had nothing to do with Nina Reiser's disappearance. He testified that the last time he saw her she was driving away from his house.

Hora, who is expected to continue his argument Wednesday, told jurors they have to answer three questions: Is Nina Reiser dead? Did Hans Reiser kill her? And, if so, was it murder or manslaughter?

He began by giving his answer to the first question, detailing all the plans Nina Reiser had made that fall, arranging for daycare for her children, landing a new job and studying for upcoming medical exams. After she disappeared, authorities found her U.S. and Russian passports at her home, along with hundreds in cash.

Her abandoned minivan was found with her purse inside, along with sacks of groceries, by that time rotting, that she had bought before going to Hans Reiser's house.

"There's no doubt she's dead. That's what all this means," Hora said. The evidence may be circumstantial, he said, but "it's powerful. It's convincing. It's persuasive and it's the truth."

Hora also covered Reiser's behavior after Nina Reiser went missing.

When a friend of Nina Reiser's called on the evening of Sept. 5 to say the mother of two was missing and asked if Hans Reiser could help with any information since he apparently had seen her last, Hans Reiser said he needed to talk with his lawyer, Hora said.

He did not call Nina Reiser.

"He doesn't even bother to pick up the phone and dial her number once! Not once!" Hora said, his voice rising to a shout. "That's absolutely mind-boggling."

Meanwhile, the Honda CRX Reiser was driving at the time went missing. "The exact same time. What a coincidence," Hora said.

When the car was located two weeks later, the front passenger seat was missing and the floorboards were soaked.

Reiser said he took the seat out to make the car more comfortable to sleep in and hosed down the floor because it was dirty.

But Hora said the real reason was the car contained evidence linking Reiser to his estranged wife's murder.

"It's incredibly incriminating that that seat's missing," he said. "It's devastating, actually."

Hora portrayed Reiser as a man obsessed with a bitter divorce battle, reading from an e-mail in which Reiser described his estranged wife as "evil."

He noted that Reiser was experienced in judo and that Nina Reiser's blood was found on a pillar near Reiser's front door.

Authorities don't know everything that happened in the case, the prosecutor said. They can't say how Nina Reiser was killed or where her body is located, he said.

But, said Hora, "we know enough."