Law enforcement officials are trying to understand how a convicted felon managed to escape from jail without anyone noticing his absence for a full day.

Esequiel Pena, 35, escaped from a private San Antonio jail sometime between Sunday afternoon and Monday afternoon. Officials believe he escaped by climbing eight stories down a fire escape, U.S. Marshals Service spokesman Thomas J. Smith said. Pena remains at large.

Pena was being held at the privately operated Central Texas Detention Facility for violating terms of his supervised release. He was previously convicted of an unspecified weapons charge and later re-arrested for a different offense, Smith said

The facility is operated by The GEO Group. A company spokesman did not immediately respond to a phone message left By The Associated Press early Tuesday morning.