King of New York

Frank White, a drug lord, is riding into New York in a limousine after being released from Sing Sing. Emilio El Zapa, a Colombian drug dealer, is shot to death, and the killers leave a newspaper headline announcing Frank's release. El Zapa's partner, King Tito, is in a hotel room with Jimmy Jump and Test Tube, who are negotiating the purchase of cocaine. Jimmy and Test Tube shoot Tito and his bodyguards and steal the cocaine.
In a suite at the Plaza Hotel, Frank is greeted by Jimmy, Test Tube, and other members of his gang, who welcome him home with money from the drug deal and King Tito's gloves, much to the delight of Frank. Frank leaves to meet two of his lawyers, Joey Dalesio and Jennifer, for dinner. Frank expresses his desire to be mayor and asks Dalesio to set up a meeting with Mafia boss Arty Clay. He and Jennifer ride on the subway. Confronted by muggers, Frank first brandishes his gun, then gives them a wad of money, telling them to ask for him at the Plaza if they want work.
Dalesio goes to Little Italy to set up a meeting with Clay, but the mafia don urinates on Dalesio's shoes and tells him it is a message for his boss that they will never work with Frank. On hearing this, Frank, Jump and other members of the gang go to Clay's social club, where Frank demands a percentage of all Clay's profits. When Clay further insults him, Frank executes the Mafioso and threatens the remaining members there. As he leaves, Frank tells Clay's men that they can all find employment at the Plaza.
The next night, Frank is confronted by Detectives Bishop, Gilley, and Flanigan of the NYPD narcotics squad. They drive him to an empty lot where they show him the body of El Zapa in the trunk. When Frank refuses to confess, Gilley and Flanigan beat him and leave him in the lot.
Frank sends Dalesio to Chinatown to make contact with Triad leader Larry Wong, who has $15 million worth of heroin. Larry demands $3 million up front and another $500,000 after the drugs are sold. Frank counters that the two should team up, then split the profits evenly. Larry turns him down and demands that Frank decide immediately whether he wants to buy the drugs. Frank declines.
Jimmy Jump and several of Frank's lieutenants are arrested by Gilley and Flanigan on murder charges, who reveal that one of Tito's bodyguards is alive and willing to testify. When Frank learns of his men's arrest, he orders his lawyers to arrange their release, despite the lawyers protest of not showing a lot of cash just to bail them out. Later, Frank and his men head to Chinatown, where they kill Larry and his gang, taking the heroin. Later, Tito's bodyguard that was willing to testify ends up dead, and no longer able to hold Frank's men for any of the charges, they are released. A disgusted Gilley spits in the face of Jump and Gilley and an angry Flanigan walk away, while Bishop has a conversation with one of Frank's attorney, angry at the result of the case.
Bishop, Gilley, Flanigan and other officers are at a bar after attending a wedding, watching Frank make a large donation to a hospital on television. Gilley, visibly angered that Frank is becoming more powerful since his release and the fact that Frank keeps evading arrest ("Ten minutes later, he's back on the streets!"), Gilley announces his intention to go outside the law in order to "get rid of Frank," suggesting that it be made to look like a rival gang was responsible in order to bring Frank down. When Bishop objects, Gilley vehemently makes it clear that he will follow through with his intent with or without his consent. Flanigan and other officers follow Gilley out the bar, leaving Bishop behind. Bishop later approaches one of Frank's attorneys, warning him to bring Frank in before it's too late.
Police officers bribe Dalesio into leading them to a nightclub where Frank and his men are partying. After one officer infiltrates the nightclub as Dalesio's drug dealer contact, Gilley, Flanigan and other officers pose as a rival gang, burst in and begin shooting, slaying several members of Frank's gang. Fleeing over the Queensboro Bridge, Frank and Jump trade shots with the police, killing all but Gilley and Flanigan. After evading their pursuers, the two men split up. Gilley and Flanigan pursuit Jump. Unbeknownst to Flanigan, Jump is able to ambush him from behind. Jump shoots Flanigan multiple times in the chest, puncturing his vest. Before Jump can execute Flanigan, Gilley appears and shoots Jump multiple times. Gilley rushes over to Flanigan and begins CPR and Flanigan dies, much to the delight of Jump. After Flanigan dies, Gilley walks over to Jump and kills him with a shot to the head.
A few days later at Flanigan's funeral, Gilley leaves the proceedings and runs to his car, distraught over losing his close friend. As Gilley is pouring his emotions out in his car, a limousine pulls up next to Gilley and gets his attention. Frank kills Gilley with a single shotgun blast and the limo speeds off before the other police in attendance can pursue.
In an abandoned warehouse, Frank's men interrogate Dalesio over the ambush the night before. Dalesio confesses to cooperating with authorities. Frank orders his men to kill Dalesio and bury the money he was paid to cooperate. After his men kill Dalesio, Frank goes to Bishop's apartment, telling him that he has placed a $250,000 bounty on every detective involved in the case. Holding Bishop at gunpoint, Frank explains that he killed Tito, Larry, Arty Clay, and Zapa because he disapproved of their involvement in human trafficking and child prostitution. Frank forces Bishop to handcuff himself to a chair.
As Frank heads to the subway, Bishop uses a hidden gun to free himself. Bishop corners Frank in a subway car. Frank takes a civilian hostage and uses her as a shield from Bishop, threatening to kill her. A standoff ensues and then a shootout begins. Frank fatally shoots Bishop, but Bishop is able to fire a shot before dying. Once the train reaches the next stop, Frank leaves the subway car and arrives in Times Square, where he hops in a taxi. In a taxi in Times Square, it's revealed that Frank has been shot in the stomach. As police officers surround the car, Frank closes his eyes, goes limp and drops his gun, implying that he has died from his injuries.

Question: Who kills Gilley?
Answer: Frank