Marvin Lane Ussery, 48, was caught on camera jumping over a 7-foot fence and breaking into the California State Prison in Sacramento. He spent seven hours in the prison before being captured.
Ussery had served time at New Folsom for robbery before being paroled in 2009.
Prison officials are investigating whether Ussery was trying to smuggle in drugs or cell phones, but they haven't yet found any contraband.
He is being held in Sacramento County Jail on suspicion of violating his parole and being an ex-convict on prison property.
State prison officials say statewide, there's a smuggling arrest every week, and cell phone smuggling has skyrocketed.