(CNN) Inmates trying to break out of prison is nothing new. But inmates breaking out, then breaking right back in? It's apparently been happening for years at a federal facility in Atlanta.

Back in January 2013, the Atlanta Police Department started investigating inmates "temporarily escaping" from the medium-security US Penitentiary in the city, according to court documents filed in what appears to be the latest unapproved furlough. Cops believe the inmates escaped through holes cut in the prison fence.

Officers first noticed a car parked near the prison fence line. The people inside wore ski masks and jumpsuits. When cops approached, the suspects climbed the fence and ran back onto prison grounds, court records show.

Inside the car, cops found bottled alcohol, 24 cell phones and two loaded handguns, documents show.

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