MADISON, Wis. — The warden of a maximum-security prison in southern Wisconsin has resigned and 11 other workers have quit, been suspended or fired in connection with an April escape, state corrections officials said Thursday.

Columbia Correctional Institution inmates James Newman and Thomas Deering escaped on April 16 by climbing over two security fences. They were caught the next day after they visited an Illinois homeless shelter. CCI kitchen worker Holly Zimdahl was charged later that month with helping Newman and Deering.

The state Department of Corrections on Thursday announced that an investigation into the escape is complete. Seven workers have been fired, one has been suspended for five days, one has been cleared and seven have been terminated, the department said in a news release.

The release didn't name any of the employees. DOC spokesman John Beard said in a telephone interview that the four workers who resigned were CCI Warden Susan Novak, who stepped down June 29; Zimdahl, who quit on May 27; guard Taylar Birkett, who resigned on May 7; and guard supervisor Kevin Boodry, who resigned on July 2.

Beard declined to name any other employees who were disciplined. He said Deputy Warden Lucas Weber and Security Director Brian Gustke ended their jobs with the department on Thursday but wouldn't say if they were among the employees terminated.

Beard also declined to discuss why the employees were disciplined. The news release said divulging any details would jeopardize safety and security at the prison.

"The results of the investigations and after-action review reflect a combination of performance failures and long-standing systemic issues related to security procedures at CCI that pre-date this administration," DOC Secretary Kevin Carr said in the news release.