Edward "Eddie" Skinner is a career criminal who used everyone he knew to get what he wanted and sold them out just as fast.
Background
Skinner spent his life as a criminal doing whatever he needed to do to get by. He served a total of 15 years for petty larceny, check kiting, boosting cars, assault and battery, burglary. He eventually started work for the ATF as an informant
Smoked
Although the detectives initially only suspect Luke Ronson, Luke reveals that he hired Eddie to scare Annette and make her life uncomfortable, but he never said to "kill her". But Eddie says that he and Luke never agreed to that. Benson believes that Luke is telling the truth, and that Eddie was the shooter. However, they still don't have the murder weapon, and without it, they don't really have a case.
Stabler is ordered to move Eddie to central booking, but when he goes to the cell, Eddie is missing, taken by the ATF because he's the key to busting a cigarette smuggling ring. Stabler cuffs Eddie and takes him away anyway, and ADA West calls DA Jack McCoy to help smooth things over.
Stabler works with Eddie undercover with the cigarette investigation, but the exchange gets botched and Eddie escapes in the confusion of gunfire. ATF is pleased with the bust, but SVU has just lost its killer.
The detectives track Eddie down to Luke's apartment, where Luke is being held at gunpoint by Eddie, who is demanding money. Stabler manages to convince Eddie to put the gun down and then arrests both Luke and Eddie. Eddie admits to killing Annette all on his own. He tries to bargain with SVU, saying that Luke told him a detailed story about the rape. If the murder charges against him are lessened, he'll give up the source of the gun he used to kill Annette.
The ATF agent is confronted by Benson and Stabler, and accused of giving the gun to Eddie. He is arrested as an accessory to murder. At SVU, Eddie and Luke are in holding, along with the ATF agent. Sister Peg visits the station to drop off evidence, a picture of Jenna and Annette with an address written in Eddie's handwriting.
Jenna arrives at the station, and Benson tells her that they have her mother's killer. They also have Luke in custody and they will go ahead with the rape trial. Jenna is brought to the "cage", and she asks about the third man in the cell. Benson tells her that it's the person who gave Eddie the gun.
As she leaves, Jenna takes the detectives by surprise when she returns to the squad room with a handgun and fires several shots into the holding cell. As Benson pleads to Jenna to stop, Stabler takes cover behind his desk and reaches for his gun inside his drawer. Jenna then turns towards them and fires one shot, hitting Sister Peg (Charlayne Woodard). Shocked, she stops firing and begins to lower her weapon. But a still alive Eddie says "you crazy bitch! I should of killed you with your mother!", further angering Jenna as she turns back to aim her weapon at Skinner, Stabler is forced to shoot to stop her. As she lies on the floor dying, Jenna reveals to Stabler that she bought the gun off the street and she dies in Elliot's arms. The camera then zooms out, showing the aftermath of the shooting.