David Brown died of natural causes in a prison hospital Thursday. He was 61, said Anthony Bear, a prison spokesman.
Brown was in a protective housing unit because of his notoriety for the killing of his fifth wife, Linda Brown, as she slept.
He was accused of persuading two teenagers —one his daughter, the other his sister-in-law and secret lover—to kill his wife. The computer businessman went on to collect $835,000 from the victim's insurance, including several policies started just months before her death.
Prosecutors said Brown coerced his daughter, Cinnamon, to take the blame. Cinnamon was 14 when she confessed to shooting Linda Brown. She spent seven years in a California Youth Authority detention facility before being paroled.
In 1988, Cinnamon cooperated with investigators after she became fed up with her father's luxurious lifestyle while she was imprisoned.
Brown paid $350,000 in cash for a house within five months of the killing. The night of the murder, Linda Brown was sleeping in a rented home in Orange County. She was shot twice at close range.
Brown told police he had left home earlier because of bickering between his daughter and his wife.
Brown was sentenced to life in prison without the possibility of parole in 1990.
The plot inspired the Lifetime miniseries, "Love, Lies and Murder."