Agent Tom Cole is the handler of Agent Doug Kersten, who was working with Kirsten when he was under the alias of "Riley" to lure and track organized criminals through their own semi-legitimate hot spot of an underground poker ring. Kirsten's ring is the scene where college student Caroline Pereira was murdered.
When the ring was raided and Agent Kirsten was arrested, Agent Cole rushed to the precinct to get Agent Kirsten released. A clandestine meeting on an intersection was arranged to reveal the truth, that Caroline was killed there, but moved to a red light district by one of the bouncers to protect Kirsten's cover. Enough evidence was preserved, and her activity was tracked, to eventually close her murder, and Kirsten's operations weren't damaged. (SVU: "Class")