The victim was shot at least one time in the chest with a rifle, which was left at the scene, according to Sgt. Jeff Decker with the Fontana Police Department.
Police have made an arrest in the case. The suspect is identified as 52-year-old Louis J. Moore Jr. Moore, who reportedly leased the apartment on Barbee Street, was arrested in downtown Riverside as he attempted to elude police.
He is being questioned by police and is said to be cooperating. Police say he will be charged with murder.
The name of the victim has not been released pending notification of next of kin.