Dr. Phillip Karr is the colleague of Dr. Max Kleberg, who was working together with him at their office to develop an impotency cream. When Max was murdered and his wife Peyton was raped, the cream was assumed to a part of it, so Karr was questioned at the office.
He remembered a problematic patient in the trial, but refusing to comment, the detectives fond the name Martin Welker, a patient on the trial arrested for attempted rape before suing the hospital and pharm company to put the culpability on them. Max's womanizing were revealed to be involved instead, clearing Karr and Welker out of suspicion. (SVU: "Tangled")