Police said a friend found the body of Gary Allen Smola, 50, on Saturday afternoon inside his house on the 1700 block of Whittier Avenue.
Investigators said Smola had been hit several times in the head with an unknown object. There was no evidence of forcible entry and nothing appeared to be missing from the home.
According to neighbors, Smola ran his own auto and boat detailing business and was always ready to help them out.
"It's almost incomprehensible. You just want to push a button and say he's back, that it was all a dream, but it's not a dream. He's gone," said neighbor Carol Ann Burr.
Neighbors said Smola lived alone and had no known enemies. Anyone with information was asked to call the Costa Mesa Police Department at (714) 754-5205.