Clay Gibson is a sex addiction patient of Cap Jackson for his sexual exchanges with teenage girls. Also have misdemeanor charges in bar fights, he was a major suspect in the series of rapes committed by one of the doctors at Jackson's clinic, Brett Kincaid.
Kincaid's arm was slashed by one woman who was raped, Holly Dimeo, with her pocket knife on her person. Thus, an undercover Stabler had the patients roll up their sleeves so he could see if Gibson had a matching wound. Instead, he had a tattoo he wanted removed, and he was eventually acquitted when Kincaid was arrested. (SVU: "Mask")