Shirley Bellinger is the first and only woman to be incarcerated at Oswald. Sentenced to die for murdering her daughter, she drove her car into a lake with her daughter in the back seat, then swam out as the car sank, leaving her daughter to drown. She swears it was an accident, but that it nevertheless "had to happen".
While she keeps mostly to herself and has a shy, charming demeanor, she shows some signs of psychological instability; shortly after her arrival, she exposes herself to fellow prisoner Timmy Kirk and essentially prostitutes herself to inmates and guards alike in return for preferential treatment. She is very polite with everyone and hardly gets angry or swears. She believes she is doing God's will, and it is suggested that she is a devout Christian.
Along with James Robson, Bellinger is one of two regulars who never lived in Emerald City. During her time on Death Row, the regular characters who have made some sort of contact with her are Leo Glynn, Tim McManus, Sister Peter Marie Reimondo, Father Ray Mukada, Dr. Gloria Nathan, Diane Whittlesey, Simon Adebisi, and Vern Schillinger.
Prisoner 97B642. Convicted December 6, 1997 - Murder in the first degree. Sentence: Death. Sentence commuted in 1999, then commutation of sentence revoked in 2000.
She exchanges a series of pornographic letters with a "secret admirer" from within her cell block. When her pen pal turns out to be fellow inmate Simon Adebisi, she rejects him because he is black, sending him off with a racial slur.
Bellinger is joined by Richie Hanlon. She asks him to expose himself to her and does not care if he is a homosexual. Bellinger and Hanlon grow close, and she is seen making a sweater for him. When Bellinger sees Hanlon and Vernon Schillinger get into a growling match, she gets worried and asks Hanlon why the two men hate each other. Hanlon explains that Schillinger is the reason he is on death row. Willing to help Hanlon, she tells him to go to the judge and say that both he and Schillinger killed Alexander Vogel together. Before Hanlon goes to see the judge, they say their goodbyes. Before lights out, she sees an empty cell and assumes that Hanlon got his death sentence overturned. She unknits the sweater she made for him, realizing she will never see him again.
Bellinger loses her final appeal and is apparently at peace with her impending death. She enlists the help of Tim McManus, who tells her Hanlon has been murdered and promises he will find out who did it. Bellinger chooses hanging as her method of execution. She tells McManus that she's on his side of the sexual harassment suit against Claire Howell.
Soon afterward, however, she learns that she is pregnant by an unknown partner. As prison psychologist "Sister Pete" Reimondo examines her, Bellinger tells the nun why she killed her daughter: she saw "orbs of fire" surrounding her and even saw a plate levitate. Bellinger insists that she has to die. Sister Pete recommends to Governor James Devlin that Bellinger be institutionalized, and Devlin then commutes Bellinger's death sentence to life imprisonment without the possibility of parole. Furious, Bellinger tells Reimondo that the nun betrayed her and demands an abortion, or she will kill "this monster inside of me". As Sister Pete is telling Bellinger she will be sent to the Connelly Institute for the Criminally Insane and will be under 24-hour watch, Bellinger screams that Satan fathered her child, and she is "the Virgin Mother".
After miscarrying the baby under mysterious circumstances, Bellinger returns to Oz. As she is walking on death row, she notices that there are three new inmates and one of them is in her old cell. She asks inmate Nat Ginzburg if he will switch cells with her; he declines. She begins to have sex with guard Len Lopresti.
As her execution date nears, Bellinger's ex-husband, Zeke, visits her and offers forgiveness. Angered, she tells him she killed their daughter because she was raped by Zeke's father and Katie was actually Zeke's half-sister. Furious, Zeke punches her in the face, knocking out a tooth.
Her execution date arrives, and she assures everyone around her she is ready to die. She talks to Moses Deyell and Ginzburg one last time, telling them she woke up with a crick in her neck and her final meal was a SlimFast milkshake. As Warden Leo Glynn and Father Ray Mukada arrive, she tells Glynn that Lopresti comes into her cell every night and has sex with her (which Lopresti denies) and tells Mukada that the father of her child is Satan in the form of a mailman (Mukada confronts Vernon Schillinger about this and Vern denies it). As she is led to the gallows, however, her survival instinct kicks in, and she violently resists her guards. She is eventually subdued and executed as planned.
Later in the series, her character narrates an episode of season 6.