Richard Overton, 81, a mathematician and computer expert who was serving a life sentence for gradually poisoning his wife to death with cyanide, died Thursday at a California hospital after being transferred from Folsom State Prison.

His daughter, Valerie Overton, said he had been suffering from diabetes and dementia.

He was sentenced to life in prison in 1995. Prosecutors portrayed him as a man obsessed with the suspected infidelities of his wife of 19 years. Janet Overton, 46, 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 the part-time professor'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. Prosecutors said her husband nursed a murderous jealousy over her alleged infidelity and described him as a devious killer who laced her eyeliner with selenium and her morning coffee with cyanide.

The investigation sparked the book Final Affair and the 1999 TV movie Lethal Vows. - AP