A convicted killer may be on the loose after escaping Monday from an Arkansas prison building -- the problem is guards aren't sure if he's actually left the facility's grounds.

The Arkansas Department of Corrections reported that the inmate who escaped from the East Arkansas Regional Unit in Brickeys was 49-year-old lifer Calvin Adams but then said it wasn't certain if he had gotten past the institution's electric fence. It was Adams's second escape attempt in 10 years.

Spokeswoman Dina Tyler said authorities were working two possibilities: one that Adams is somewhere on the prison grounds and another that he is on the run outside the facility.

“Anyone with information on his whereabouts is asked to contact their local law enforcement,” the department said after reporting the escape attempt.

Guards discovered Adams was missing during the 4:30 a.m. roll call, KAIT-TV reported.

Ten years ago Adams and another inmate walked out of the Cummins Unit in Lincoln County wearing guard uniforms and drove away in a car that was left for them. They were arrested in New York state four days later when a trooper tried to stop their car for speeding.

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They were caught in Hopewell after the car crashed and they tried to flee on foot.

The guard uniforms the two were wearing were made in the prison.

Adams was convicted of capital murder in 1995 and was sentenced to life in prison with no chance of parole.

A year earlier, he kidnapped 25-year-old Richard Austin and his pregnant wife, Cassandra, from their home, in an effort to rob a bank where Austin worked as the vice-president, KAIT reported.

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He took them to a remote area and shot them when he learned Austin didn’t have access to the bank vault.

He drove the couple’s car back to their home and set it on fire to cover up the crime, according to the station.

Austin died after being shot three times.

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His wife walked to a farmhouse for help despite suffering a gunshot wound to her chest and a fractured skull, the station reported.

The Associated Press contributed to this report.