A Shelby County corrections officer resigned from his job Dec. 21 after a Shelby County Sheriff’s Office investigation showed the officer was involved in an improper inmate movement.

On Dec. 16, The Sheriff’s Office received a tip from a county inmate who told officers two female inmates “were allowed to leave their cells during the middle of the night,” according to a Sheriff’s Office press release.

The inmates did not leave the correctional facility, according to the press release.

After the Sheriff’s Office completed an administrative investigation into the incident, they discovered inmate movement within the jail was irregular during the time the incident reportedly occurred.

“The investigation further identified a male corrections officer was responsible for this improper inmate movement,” read the press release, which noted the officer resigned voluntarily before the administrative investigation was completed.

The Alabama Bureau of Investigation is conducting a criminal investigation of the case, and will determine whether any criminal acts occurred during the incident.

“While it may be too early in the investigation to determine if a crime was committed, it was clear to me that this employee could no longer work at the Sheriff’s Office,” Shelby County Sheriff Chris Curry wrote in the release.

“We asked the ABI to see if criminal charges are warranted,” Curry added. “We are going to provide them with anything and everything they need to accomplish that.”

As of Dec. 21, the investigation was ongoing, and authorities had not released the correctional officer’s name.