looking at her ex-boyfriend roc, his name was scrawled in blood at the crime scene. he insisted he didn't kill her. was there more to the bloody clue than met the eye? forensic specialist anna cox was trying to unlock what her naked eyes could not see. when she did, her discovery would send the investigation in a completely different direction. here is dennis murphy with written in blood. >> the handwriting was on the wall and forensic specialist anna cox was intent on breaking down the three letters in blood, roc. you would spend hours looking at these letters? >> i did. >> you actually cut the sheet rock out of your place and took it into your lab? >> yes. i have to look at those letters after everything about them. >> using a high powered