CBS

Season 3: Episode 16 - Quid Pro Quo

Quid Pro Quo: Erin is approached by a man who asks for her help with a cold case. He believes his daughter Jenny was murdered by her boyfriend Richard, a man from a rich and well-respected family, but was never convicted. Erin and Danny follow leads to prove that Richard's alibi had lied for him. Still needing to place him at the scene of the crime, Erin lures Richard to meet her for a drink and comes away with a sample of his DNA that turns out to be only a close match to the blood left on Jenny's necklace. Danny and Erin realize it was Richard's father Preston who killed her and they are able to stop Richard just as he is about to shoot his father. Meanwhile, Jamie stops his friend from going through with a false lawsuit against a friend of Danny's after the two have a brawl during a basketball game. Garrett comes clean about his disdain for Frank's tendency to avoid playing politics.