A Torrance Superior Court jury deliberated for over four hours before finding Michael Lubahn Clark, now 59, guilty of second-degree murder.
Carol Jeanne Lubahn, 28, was last seen alive on March 31, 1981. Her body was never found.
The couple -- who were high school sweethearts -- were the parents of two children and had been married 10 years when she disappeared.
According to Deputy District Attorney John Lewin, Clark killed his wife in their home on the 17600 block of Cranbrook Avenue. Prosecutors contended the couple fought the night she disappeared and Clark feared his wife was going to divorce him.
Clark claimed that his wife left the home in the middle of the night and never came back.
Clark faces 15 years to life in state prison when he returns to court on Dec. 12 for sentencing.