Devon is the guy whose name shows up on Kylie's schedule, on her PC in her apartment. Run the schedule through your lab computer to get Devon's rap sheet. Turns out he's got one. Compare it to the prints from the TV and sure enough, there seems to be a match! Go into cop-land and talk to him.

When you first mention Kylie he's upset to learn that she's dead. Who would kill such a sweet kid? He last saw her 2 weeks ago. Sure, he has some cuts.

Get a DNA and hair sample from him, just like you did with Bert. Head back to the lab with them. The DNA sample matches the material under Kylie's nails. And the hair matches the one you found in the bed.

Now when you chat with Devon, ask him about that Hep C. You go through a story about how he found out he'd been "killed" by her, and that he wanted to kill her in return.

It took about an hour of playing time, and I got 95% complete with 6/10 extras using this path.

CSI Crime scene Investigation Walkthrough