Law enforcement officials are trying to understand how a convicted felon managed to escape from a privately owned jail across the street from the police headquarters 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. He remained at large Tuesday but was thought to be in the San Antonio area, said U.S. Marshals Service spokesman Thomas J. Smith.

Pena apparently escaped by pulling back chain-link fencing around a rooftop recreation yard and climbing down an eight-story fire escape, Smith said.

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, which has nearly 700 inmates, is operated by The GEO Group. Spokesman Pablo Paez said Tuesday the company is assisting the U.S. marshals' investigation, but he would not say why it took so long to discover Pena was gone.