Investigators in Atlanta are trying to determine who gave rap artist T.I. (search) permission to shoot a video in a Fulton County jail, using real guards and prisoners as extras.

In the video, which was shown before his concert Saturday, T.I. is seen posing behind bars, then being escorted out of a cell by real, uniformed guards.

T.I., whose real name is Clifford Harris, is serving time in a work-release program in nearby Cobb County Jail for violating probation on a drug violation. He is allowed to leave jail to work on his rap career, so he's not in trouble for shooting the rap video.

But the identity of the person who gave T.I. permission to shoot his video there remains unknown, and Fulton County Sheriff Jackie Barrett claims she had no knowledge of the shoot.

To make matters worse, a female prisoner escaped while the video was being shot, although Barrett insists the two incidents are unrelated.

"As we locked the building down because of the escape, all of a sudden it comes to light that there's a video crew upstairs doing something that neither me nor any of my senior staff had any knowledge of," Barrett said. "And I want to make that clear that this was a totally unauthorized event that occurred."

Nonetheless, Barrett is taking the heat for the incident.

"The sheriff should resign for the safety of our citizens, for the safety of our officers, for the good of this community," said Fulton County Commissioner Karen Handel. "In fact I implore her to do the right thing and step down so we can restore order to our jail."

Go to the video box at the top of this story to watch a report by Fox News' Jonathan Serrie.