A jailer or prison keeper was responsible for guarding prisoners and maintaining security in the detention facility. In the ancient world, this role carried significant liability—if prisoners escaped, the jailer could face execution. This explains the Philippian jailer's near-suicide when he assumed his prisoners had fled during the earthquake. The jailer's conversion narrative demonstrates how the gospel reached across social boundaries, transforming even those whose occupation involved coercion and confinement into brothers in Christ.