Antwon Mitchell is a drug kingpin who, having been released from a lengthy prison sentence, tried to reinvent himself as an upstanding Black community leader out to aid the African-American citizens of Farmington. However, he has secretly secured power as the most powerful drug boss in the district, leading a gang called the One-Niners and secretly flooding Farmington with black tar heroin.
He is currently imprisoned for personally gunning down an 14-year-old police informant, ordering the kidnapping and stabbing deaths of two cops from The Barn, and trying to blackmail Detective Shane Vendrell into murdering Detective Vic Mackey.
Mitchell's childhood was not a pleasant one. He was an overweight loner who was too frightened to protect his young sister from their sexually abusive father. His mother later shot and killed his father, for which she was sentenced to life in prison. While imprisoned, she was impregnated by a prison guard and bore Antwon's half-brother, Jason Porter.
During his early criminal life he and Rich Nelson had a rivarly which Nelson tried to nail Antwon nine times. During these times he killed three crack dealers on Olympic and stabbed a cop in the leg with Antwon getting away with it every time. Eventually Antwon was arrested on a trafficing charge and sentanced to thirteen years in prison. He eventually got out on probation and waited four months before re-entering the One-Niners as their leader.
Mitchell has a longstanding feud with Captain Monica Rawling, the officer who sent him to prison. The two square off at a community meeting regarding the new implementation of Rawling's seizure policy. The events of the fourth season unfolded from this confrontation.
Detective Shane Vendrell, attempting to emulate his former mentor Vic Mackey, actively pursues a possible partnership with Mitchell. With Vendrell on Mitchell's payroll, he and his partner, Army Renta help Mitchell eliminate his rivals and ultimately become head of the One Niners. Not satisfied with simply paying cops do his dirty work, Mitchell seeks to dominate Shane and his partner. After being provoked several times by Vendrell, Mitchell's thugs attack him and Renta in a warehouse. With his foot on Vendrell's neck, Mitchell murders Angie Stubbs, the 11-year-old girl who had informed on his drug ring, costing him a great deal of money and heroin. He uses the body to blackmail the two into murdering Mackey, whom Mitchell sees as the biggest threat to his drug business. However, instead of doing as he was told, Vendrell asks for Mackey's help. After finding the girl's body with a hidden camera, they catch footage of Mitchell restating his offer of "a body for a body." This ultimately forces Mitchell to plead guilty to the girl's murder and attempting to order the death of a police officer.
After helping David Aceveda kill prison inmate Juan Lozano, Mitchell tries to free himself from his sentence by using information regarding the inner workings of a Salvadoran drug cartel in order to get a DEA immunity deal without disclosing any information about the cop killings in his territory. However, the deal is ultimately voided when Mitchell's nemesis, Captain Rawling, sacrifices her job by bringing down the Salvadorans herself, making sure that Mitchell never gets a chance to leave prison.
Since his imprisonment, Mitchell has risen to a place of power within the prison, essentially running it. He also supports a revival of the fading One Niners gang and even attempts to run his drug ring from inside. He also makes a deal with Internal affairs Lieutenant Jon Kavanaugh to give up information on the Strike Team in exchange for their incarceration at his prison. However, he makes a separate deal with Mackey to provide financial assistance for the One Niners in exchange for Curtis "Lem" Lemansky's protection in prison. The deal goes through, but only pulls in a small haul of cash. Combined with Kavanaugh's investigation of the prison system that puts a cramp in Mitchell's personal comfort, Mitchell declares the deal off and vows that he will have Lemansky murdered, no matter which prison he is sent to.
Mackey and the Strike Team hide Lemansky in a trailer park. The heat brought on by IAD in response leads to Lemansky's murder at Vendrell's hand. After Lemansky's death, Mackey visited Mitchell in prison, hoping that he is the one who ordered the hit. Mitchell is proud to have Vic's blame for all the ills of the world, but admits that he had nothing to do with the murder.