Niles, 33, of Corona was drafted and waived by the Philadelphia 76ers in 1979. He signed with the Phoenix Suns as a free agent in 1980 and remained with the club for a year before being waived.
He continued his career with the Lancaster Red Roses of the Continental Basketball Assn.
Niles showed no emotion while listening to the verdict in Riverside County Superior Court. Jurors deliberated 13 hours before finding that Niles conspired with Noel Jackson of Los Angeles to murder Sonja Niles Dec. 13, 1984. She died of a shotgun blast to the head from close range.
Monday, a separate jury convicted Jackson of murder.
The prosecution contended that Niles arranged to pay Jackson $5,000 to kill Sonja Niles, planning to get the money from a $100,000 life insurance policy.
Eash man accused the other of the murder.
A witness testified that Niles said he wanted his wife killed because she "messed me out" of money from basketball.
The jury found a special circumstance of murder for financial gain, so the death penalty could be imposed.
In 1978, Niles was a member of Fullerton's "Cinderella" team that reached the NCAA regional finals. During three years at Fullerton, Niles, a forward, averaged 12.4 points per game.