why was peacemaker in jail

Peacemaker, aka Christopher Smith, was in jail because he was sentenced to a 30-year prison term for crimes committed as a vigilante, including murder. He served four years of this sentence before being recruited by Amanda Waller to join the Suicide Squad. During the Suicide Squad mission, he was shot and trapped under rubble, after which he was hospitalized. Despite his recruitment and partial sentence reduction due to missions completed with the Suicide Squad, he still had years remaining to serve. His time in jail was for violent offenses tied to his ruthless approach to achieving "peace," often involving excessive violence and killing.