SANTA ANA, Calif. - Richard Overton, a mathematician and computer expert who was serving a life sentence for gradually poisoning his wife to death with cyanide, has died. He was 81.

Overton's daughter, Valerie Overton, said her father had been suffering from diabetes and dementia. He died Thursday at a hospice in Northern California after he had been transferred from Folsom State Prison.

Overton was sentenced to life in prison in 1995. Prosecutors portrayed the part-time professor as a man obsessed with the suspected infidelities of his wife of 19 years.

His wife, 46-year-old Janet Overton, collapsed in January 1988 while leaving the couple's Dana Point home. She died shortly afterward, and authorities initially revealed no evidence of foul play.

But after Overton's first wife, Dorothy Boyer, told authorities he had tried to poison her in 1973 after they had divorced in 1969, a new investigation was opened.

Cyanide was found in Janet Overton's blood and stomach contents, prompting experts to conclude she had been poisoned.

Prosecutors said Overton nursed a murderous jealousy over Janet Overton's alleged infidelity and described him as a devious killer who laced her eyeliner with selenium and her morning coffee with cyanide.

The criminal investigation sparked the book "Final Affair" and a 1999 TV movie, "Lethal Vows."