Paid in Full

Ace (Wood Harris) is a young man from Harlem stuck in a dead end job at a dry cleaning shop. His sister's boyfriend, Calvin (Kevin Carroll), is a local cocaine dealer who tries to lure Ace into the drug trade with promises of fast money and women. Ace resists Calvin's temptations, not caring for his unsophisticated ways. Likewise, Ace's close friend Mitch (Mekhi Phifer) is a flashy, popular drug dealer who exposes Ace to drug dealing lifestyle. When Calvin gets arrested on drug charges, Ace ends up filling his position on the street. This happens after Ace starts getting cocaine from Lulu, one of the customers at the dry cleaners shop. Lulu has a top-quality supply of cocaine which Ace sells on the street at a cheap price, quickly luring away customers from other drug dealers. Ace operates on the mantra that there is plenty of money to go around and that everyone can "live and maintain." While Ace is building up his drug operation, Mitch is arrested for killing a stickup man who robbed one of his workers. When a fight breaks out between Mitch and another inmate, Mitch is aided by East Harlem inmate Rico (Cam'ron) who impresses Mitch by his ferocity and show of solitude.
Mitch is able to beat his murder charge and both him and Rico join Ace's drug empire. The trio become extremely wealthy, buying foreign cars, jewellery and expensive champagne. Ace continues to more or less stay behind the scenes, while Mitch returns to his flamboyant lifestyle as a popular hustler. Rico is a ruthless enforcer who worries Ace with his overzealous behavior and high-profile lifestyle. When Calvin is released from prison, he tries to regain his position of power on the streets. Ace gives him a job overseeing his old drug spot, but Calvin feels dissatisfied with his menial position. When Ace refuses to let Calvin run his old block, Calvin attempts to rob Ace. Calvin grows increasingly anxious and kills two of Ace's relatives while Ace survives his shooting despite being shot in the head. Feeling physically and physiologically defeated, Ace decides to quit the drug trade. Rico, who kills Calvin in retaliation, strongly disagrees with this decision. Mitch understands Ace's perspective that the drug game does not reciprocate any love or generosity. Mitch decides to stay in the drug game because he loves the hustle, comparing himself to professional basketball players that continue to chase glory despite having enough money to retire.
While Ace is recovering, Mitch's kid brother Sonny is kidnapped for ransom. Mitch tries to quickly raise cash to pay the ransom by selling as much cocaine as Ace can get his hands on. When Mitch reaches out to Rico for help with his campaign, Rico murders Mitch and steals the drugs that Mitch intended to sell to save Sonny. Rico lies to Ace about his whereabouts that night, not knowing the Mitch had told Ace they were going to meet up the night of his death. Ace settles the issue by giving him the contact to a pair of undercover FBI agents Ace had spoken to and avoided previously.
Rico is arrested and is last seen in custody giving up information on his out-of-town drug connections in Washington D.C. in order to avoid a 25-to-life sentence. He refuses to inform on anyone in Harlem, intending on reclaiming his position when he is eventually released from prison. Sonny's kidnapping and subsequent murder were orchestrated by his own uncle who resented Mitch for not providing him with money and for kicking him out of his family's apartment. Ace manages to retreat from the criminal underworld and makes a new life for himself and his family using diamonds that he had previously found in Lulu's apartment after his death.

Question: Who kills Calvin?
Answer: Rico