A 54-year-old suburban Detroit man with a history of mental illness and substance abuse will spend the rest of his life in prison for beating his 87-year-old father and 85-year-old mother to death with hammers.

An Oakland County jury found Jeffrey Maurer guilty Friday of first-degree premeditated murder. He will be sentenced Tuesday.

Sheriff's deputies found the bodies of William and Gayle Maurer Jan. 19 in a vehicle inside the garage of their Rochester Hills home. They were bludgeoned two days earlier with two hammers and a heavy tea kettle.

Jeffrey Maurer lived with his parents. Prosecutors have said he wanted their money.

Defense attorney Michael McCarthy has said the slayings were "spur of the moment" and not planned.