>> reporter: turns out, that was the same argument, tony tung's attorney, robert kalish made to the jury. why, he asked, would tony kill rob a year after rob had shown him the bed where he had sex with his wife? >> if he didn't kill him right there and then, he wasn't going to kill him at all. because that was the time to do it, with his bare hands. >> reporter: according to kalish, investigators never seriously considered the possibility that someone else may have wanted rob cantor dead. >> tony was the only suspect. >> reporter: another potential suspect, kalish said was the stranger that had been spotted near the cantor home shortly before the fire. charles johnston was the neighbor who reported the man to police. >> i saw an older gentleman approximately 65-70 year old white male with a red cap on and white hair.