theresa insana came home to resin niagara falls, new york. s and family were living with equal measures of agony and bewillederment. who had killed theresa, and why? >> theresa was such a good person. she didn't do anything bad to anybody. there would be no reason to kill her. >> and as their grief settled in, theresa's former fiancee', jeff fenton, was being questioned about the murder. >> it's obviously something that i had nothing to do with. >> also questioned was fenton's new girlfriend, melissa ball. she was 23 and worked with jeff and theresa at the rio. >> i mean, i don't want to scare you or anything, but your name has come up as just a person that we need to talk to. >> first melissa ball confirmed jeff's alibi, saying they were both at that car dealership the evening theresa was murdered. >> he was with me all day tuesday and tuesday night. he was with his little sister and me wednesday night. and there's no way in hell he would ever hurt that woman. >> but melissa ball also admitted to police that she did not exactly favor jeff's d