Four former officers at a north Alabama prison have been charged with bribery and ethics law violations, the state prison system confirmed.

The four men face charges of using their public positions for financial gain and bribery, a spokeswoman for the Alabama Department of Corrections wrote in an email. The four had worked as correctional officers at Limestone Correctional Facility. All four resigned on Nov. 22, according to the prison system.

The prison system released few details about the charges. However, at least some of the accusations relate to contraband being brought into the prison, according to court documents.

The charges were filed after an internal investigation by the Alabama Department of Corrections Law Enforcement Services Division, the prison system said.

In a separate incident, an Alabama prison captain and a former officer were arrested last month on similar bribery and ethics charges, the state prison system said.