At about 9 p.m. Monday, the man's son called a friend to check on his father, who lived at an apartment complex on North Braeswood near Renwick.
When the friend arrived, the door was unlocked and the father was dead.
According to police, the father, believed to be in his 70s, had a "great deal of trauma" to his body.
A bloody hammer was found nearby.
At this point, neighbors have told police they didn't hear anything suspicious.
No one is in custody, and police haven't said if they have a suspect.
The man has not been identified.
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