Convicted bank robber
Callum Donovan was a man who spent 16 years in solitary confinement while in prison.
Early in his sentence, the Aryan Brotherhood, a white supremacist prison gang, told him to join them. When Donovan refused, a fight broke out, one of the supremacists never walking again. Donovan was sent to solitary confinement, spending enough time alone to become paranoid. When the guards came to get him out, Donovan, under the belief they were out to kill him, attacked them. They left him in the Hole until six months before his release.
His paranoia and desire to never go back to the Hole caused him to push SVU detective Elliot Stabler off a building. Although wanting to see him punished at first, Stabler's intentions changed when he heard Donovan describe the psychologically-damaging horrors from being in the Hole. As an experiment, Stabler voluntarily spent three days in the Hole, only to experience the same torment Donovan went through.
When Donovan was convicted of Stabler's attempted murder, ADA Sonya Paxton arranged for him to be released from solitary confinement.