Dr. Wilson Bowman appeared in the episode Red, White and Blue. He was the killer of Lucy Greene.
Dr. Bowman was skimming medications and selling them to the black market. He was recently divorced and his ex-wife took everything in the divorce. He was paying alimony, child support, and maintaining her way of life, while he was being financially wiped out.
Lucy discovered the discrepancies and was wanting to launch a full investigation. Lucy didn't know Dr. Bowman was behind it. He lured her into an alley claiming there was a patient, and then slashed her throat.