Modesto police said Kelli Pratt wanted her feeble 65-year-old husband to have sex with her the night of Oct. 7.
When Arthur Pratt refused, police said, his 45-year-old wife held him down and bit him repeatedly during a savage attack that ultimately killed him.
Arthur, whose skin was riddled with more than 20 deep tooth marks, died Sunday at Doctors Memorial Center in Modesto -- six days after the attack.
Detective Sgt. Al Carter said Wednesday that Dr. Jennifer Rulon, a Stanislaus County forensic pathologist, believes that the case will be ruled a homicide and that the bites are the likely cause of death.
"He was able to dial 911 that night," Carter said. "We have a tape recording of him screaming while she was biting him. When officers arrived, he was screaming that he'd been assaulted. She fought with the officers and tried to bite them, too."