More than 30 years after a man strangled his male sex partner and slashed his throat in San Jose, Calif., his lawyer says he acted in self-defense.The prosecution, however, says David Owen Rodriguez killed Robert Oswald to rob him, and then tried to cover it up by slashing Oswald\'s wrists, the San Jose Mercury News reported.The killing occurred March 18, 1981, but police did not discover Rodriguez\'s involvement until 2008 when a crime lab performing a cold-case check found bloodstains on a razor and a towel matched his DNA.Deputy public defender Sylvia Perez McDonald told jurors Rodriguez -- then 19, and now 49 -- acted in self-defense when Oswald, who had a history of psychiatric problems, came at him with a razor and a knife.\"Kill or be killed -- those were the options David Owen Rodriguez had that night,\" Perez McDonald said.rosecutor Dan Fehderau portrayed Oswald, 39, as \"helpless\" and said Rodriguez was much younger, bigger and stronger. Fehderau said Oswald had picked up Rodriguez for casual sex and was \"beaten about the head, cut up, manually strangled, carved and stabbed.\"The prosecutor said evidence would prove Rodriguez went through Oswald\'s left pants pocket and ripped a chain off his neck. Oswald\'s voice box had been crushed and his mouth was slashed to form a so-called Joker\'s smile, the Mercury News said.Fehderau said Oswald was a methamphetamine addict with a personality disorder but said his past should not influence the jury.\"This case is about murder and justice delayed -- about a man who did not deserve to die,\" Fehderau said.