Mario Rivera is the boss of the murder victim Leonard Levitt. Rivera tells Beckett and Castle that Len has changed the bulbs in the underground passages in all of New York. But Rivera otherwise has no idea about his employee. Later Ryan has found evidence that Rivera wanted to sell the used bulbs secretly to Costa Rica. He was also formerly a sniper in the military. Rivera finally admits the illegal sale, but his transaction was exactly the time of the murder of Lenny, and this place was under police surveillance, so he has an alibi.