Mr. Parineh, 67, faces a mandatory sentence of life in prison without the possibility of parole, said San Mateo County District Attorney Steve Wagstaffe.
The jury, which had been deliberating since May 20, decided that Mr. Parineh had committed murder for financial gain. His wife's life was insured for $30 million, and he had seen his real-estate holdings, valued at $152 million in 2007, melt away to the point that he had lost all his income, and had applied for government assistance, prosecutors said.
Deputy District Attorney Jeff Finigan had repeatedly pointed out to the jury the improbability of the defense attorney's argument that Mr. Parineh's wife had committed suicide. Four 0.38-caliber bullets were found in Ms. Parineh's bedroom. One had gone through her cheek and mouth, one had missed, and one may have grazed her head. The fourth shot went through her brain and killed her, prosecutors said.
"Is this the most extreme, superhuman suicide ever? No. This is murder plain and simple," Mr. Finigan told the jury.
Defense attorney Dek Ketchum attempted to establish in the jurors' minds a reasonable doubt that Mr. Parineh had committed murder. "It was a suicide gone horribly wrong by a woman not familiar with the gun," Mr. Ketchum said in his summation. "She shot herself, she struggled, she missed and then she killed herself."
San Mateo County Superior Court Judge Lisa Novak presided over the trial.
Mr. Parineh's next scheduled court appearance is at 1:30 p.m. July 12 for a pre-sentencing report, sentencing hearing and imposition of a sentence, prosecutors said.