to look at the calendar because i don't know where i was that day but i guarantee you i wasn't in oldsmarad been with, where i lived. >> so are you getting a serious grilling? >> right. he ends up telling me that we found your name in blood on the wall. >> roc? >> yeah. so, obviously, i'm a suspect. i acknowledge that. i mean i'm looking at murder. i'm getting somebody's talking to me about a murder. >> roc waived his right to a lawyer and agreed to give fingerprints and swabbing. it looked as though police found yet another cooperative boyfriend of the victim. >> i said, if you are looking for fingerprints, they're all over that home. i lived there for a year, so you're going to find them. >> did you lose your patience? >> i did lose my patience when they cut the end of my finger off taking a fingernail. you take the end of my finger off, now i'm done. >> roc's cooperation had an edge to it. was he really trying to cover his tracks? detectives were determined to find out. and they put that bloody clue under the microscope. were those three little letters really what they had seen? >> com