The opening of the trial for a man accused of killing his wife — even though her body was never found — was postponed Monday, and the judge or lawyers in the case did not immediately give a reason for the delay.

Nina Reiser, 31, disappeared last year after shopping for groceries and dropping her two children off at her estranged husband's house in a quiet section of the Oakland hills.

Prosecutors say there's no great mystery about what happened; they believe they can prove she was killed by her husband, Hans Reiser, even though her body hasn't been recovered. But the defense has maintained there is no proof Nina Reiser is dead, let alone slain, and she may very well be secretly living in her native Russia.

Opening arguments were rescheduled for Tuesday.

The challenge facing prosecutors is to build a convincing case out of the DNA and circumstantial evidence, said attorney Ivan Golde, who briefly discussed joining in Reiser's defense but ultimately did not get involved.

"You just start adding up block after block," he said. "At the end of the day, will it be strong enough? You never know how it will play out."

Nina Reiser's minivan was found six days later with her purse and groceries still inside.

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

Seven-year-old Rory Reiser later told police he never saw his mother leave the house. But during a pretrial hearing, the boy testified that he saw his mother drive away. Jurors aren't likely to hear either story since both the boy and his sister are now in Russia with their maternal grandmother, who has begun custody proceedings.

Nina, a trained doctor, and Hans, a 43-year-old software engineer well known in programming circles, had met in Russia and married in 1999. They were separated by 2004 but had never divorced. They were fighting over custody of the children.

During the pretrial hearing, defense attorney William Du Bois suggested that Nina and her family had ties to a Russian spy agency. There was also testimony that Nina had dated a sadomasochist.