BROOKLYN - Police have arrested an elderly man suspected of stabbing a 21-year-old to death in Bushwick. 

According to investigators, 81-year-old Nicholas Diaz is facing manslaughter and criminal possession of a weapon charges for killing Kevin Rivera Sunday afternoon. 

Sources tell News 12 that the stabbing stemmed from a domestic dispute involving the victim's girlfriend, and that Diaz is one of her relatives.  

Rivera was found stabbed in the chest inside his girlfriend's apartment on Broadway. He was pronounced dead at the hospital.