OAKLAND -- Computer engineer Hans Reiser testified Monday that one of the last things he said to his estranged wife Nina before she disappeared on Sept. 3, 2006, was to accuse her of being an embezzler.

In his fourth day on the witness stand in his trial on charges that he killed her, Reiser, 44, said Nina Reiser, who was 31 when she disappeared, came to his house in the Oakland hills about 2:20 p.m. that day to drop off their two children as part of a compromise agreement in which they shared custody of them that weekend.

Reiser said his relationship with Nina was improving in terms of spending time together with their children but medical and legal custody of their children remained contentious issues.

Reiser said he told Nina that "she'd embezzled money" from his file system business and accused her of forging his name on legal papers.

But he said that after he and Nina spent about an hour talking about their children and their divorce, she kissed the children good-bye and walked out his house alive.

The body of Nina Reiser, who was born in Russia and was trained as a physician there, has never been found, despite extensive searches in the Oakland hills and elsewhere.

But in October of 2006 Hans Reiser was charged with killing her because prosecutors believe that DNA and blood evidence proves that he killed her.

He has pleaded not guilty to the charges against him.

Reiser's attorney, William DuBois, has said that Nina may still be alive and be in hiding somewhere, possibly in Russia.