I'm playing episode 3 - Tapped Out

I'm totally stuck at this certain part after interviewing the victims stepsister and nurse and finding the fake nail pieces in the garbage can in the John Baretts bedroom and on the victims hand.. I processed everything in the lab, the shoe prints the shoes in the bedroom. It showed that it matched. I did the chemical test on the nails. Got the underwear from the bed with the seman on it but can't do anything with it. I'm just really stuck and lost. Can anyone help me?