The man was found dead after the Police Department's search warrant team went at about 9 p.m. to a home in the 800 block of South 45th Street to serve a search warrant, police Lt. Mark Gagan said.
No one answered at the front door, so officers forced entry into the home and found the victim dead from some sort of trauma, Gagan said.
Authorities are treating the case as a homicide, but will wait for the Contra Costa County coroner's office to perform an autopsy to determine the cause and time of death. Gagan said it did appear that the victim had died just a few hours before police arrived.
No arrests have been made and no motive has been established for the homicide, he said.
Gagan said the case was odd because of the way police found the body of the man, whose identity has not yet been released.
"It's a very unusual way for us to become aware of a homicide, making entry into a residence for another criminal investigation," he said. "We had no calls, and no indication that there were any problems in the home other than the investigation into other criminal activity."
Authorities are offering a $10,000 reward for any information that leads to an arrest and conviction in connection with the death. Anyone with information is asked to call Richmond police Sgt. Lee Hendricsen at (510) 620-6616. People wishing to remain anonymous can call (510) 232-TIPS.