Dead Men Walking is an independent 2005 zombie film directed by Peter Mervis and written by Mike Watt.
The Centers for Disease Control and Prevention (CDC) don't know if he is right or wrong, so he is sentenced to Haywood Maximum Security Prison.
Travis and the new inmates arrive at the facility and are put in a line where they are evaluated by corrections officer, Lieutenant Sweeney, telling them that he is "top of the food chain" in the prison.
The bitten guard dies and Mahler, Sweeney, Dr. Goring, Samantha and Johnny try to determine if the virus is real.
Sweeney, Jenkins and Mahler devise a plan to move through the building and gather all the uninfected staff to barricade themselves in the staffroom on the other end of the facility while the guards venture out to kill all infected.
Sweeney, Mahler, Keith, Jenkins and many other guards make it to the cell blocks to see that all the inmate and staff left have been infected and zombified.
Seeing that many more are coming, they split up and run inside cells and lock the gates, separating them and keeping firing distance.