A Fairfax County jury found a man not guilty of murder Friday in the killing of his uncle during a dispute in their Merrifield area apartment in August 2012, attorneys said.

Jose Ivan Lopez Castro, 21, was accused of stabbing Oscar Rivera, 38, after a fight over the fidelity of Rivera’s wife. Rivera later died from the wound.

But Deputy Public Defender Dawn Butorac, who represented Lopez Castro, argued in Fairfax County Circuit Court that her client was acting in self-defense during a violent clash that came after a night of drinking.

“It was a clear case of self-defense,” Butorac said. “The fight was started by the decedent and the knife was introduced by the decedent.”

Fairfax police found Rivera’s body in the bathroom of the apartment, which is in the 9100 block of Barrick Street, on Aug. 7, 2012. Rivera was slumped behind a bathroom door with a stab wound to his abdomen. Lopez Castro was arrested soon afterward.

A Fairfax prosecutor declined to comment on the case.