why would tony kill melissa in the first place? debra villegasvery jealous and angry with melissa because she'd virtually replaced him in the household. >> was melissa helping you through this difficult time in your life now, through this divorce? >> yes, ma'am. >> and that was the theory. in order to get back at debra, he killed her best friend. >> you have these domestic homicides all the time but this had a twist to it because he didn't kill debra. >> then tony and debra's 23-year old son, caleb, was called to testify against his father. the usual blank stare on tony's courtroom face changed as his son recalled how his father blamed melissa for the divorce. >> did he tell you that it was melissa's fault? >> he -- he believed that she had a part in it. yes. >> did he tell you that he was mad at melissa about this? >> yeah. he was mad about the whole situation. >> oh, and there was one more thing. remember melissa's jacket, the one found in her suv? tests showed tony's dna on the jacket. prosecutors believe tony wiped his nose with it after bein