their families together in their struggle to prove they were both murdered. though neither of their boyfriends have been arrested, the families believe they are responsible. and as the wait for answers from police becomes unbearable, kathy kupka turns to a private investigator for help. >> in the beginning, we were doing a ton of work at the beginning every day. gil was always there. and then it slowed down. we laid a really good foundation, got everything clear. >> they had to learn everything they could about their prime suspect, rudy persaud. they had to start thinking how he was thinking. rudy had dated kristine briefly. she had gotten pregnant. >> he was desperate. his wife knows. she could be pushing him to get something done quick. so who are we going to ask? rudy is very controlling, you know. he had to know exactly what happened. >> they systematically met people close to him. >> we found out a lot, just about his family. who he hung out with.