A deadly mystery illness at a state prison is putting inmates and employees at risk.

One inmate has died and 25 others are now under watch at the Putnamville Correctional Facility as Indiana state health officials and the Centers for Disease Control try to figure out what's making people sick.

In an update Monday afternoon, the Department of Correction revealed at least four inmates are now in critical condition. Officials still don't know the source of the quickly spreading illness. All they can say is that it presents with flu and pneumonia like symptoms, including shortness of breath.

The DOC says it has replaced 75 air handling filters and  provided masks and hand sanitizer to all inside the prison. Visitors are not allowed until further notice.

Those living near the prison are still concerned.  They're worried about what their community has been exposed to as workers have been in and out of the facility prior to the outbreak on Friday.

13 Investigates spoke with a former "America's Most Wanted" fugitive, Wade Meisberger, who said he warned the state in January 2015 about potential problems.

Meisberger describes "The State Farm," as it's called, as an incubator. He showed 13 Investigates letters he sent to both prison officials and Gov. Mike Pence, calling Putnamville's sanitation program ineffective. 

"You just can put that many people in such a little amount of space and expect it to be clean and stay clean and for there not to be any kind of germs or bacteria," said Meisberger.  "Just because you're in prison doesn't mean that you should be subjected to inhuman conditions," he added.

In a response letter, Indiana's Executive Director of Adult Facilities said the state was commended for its sanitation program at Putnamville.

Meisberger, who spent 18 years in the DOC,  was convicted of murder in 1991after getting into a drunken fight with his best friend and killing him.  Meisberger said he was 19 years old at the time.  He was also on the run after a parole violation in 2007.  Police said he faked his own death by jumping off a Kentucky Bridge.  He was re-arrested in 2012 after posting videos on YouTube.  

Meisberger served time at Putnamville from April 2014 until his release in April 2015.  He told 13 Investigates he has turned his life around and at a time when he could simply keep quiet, he's chosen to speak out because he believes the outbreak could have been avoided.

This story will be updated.

Source and Video:  http://www.wthr.com/story/31051430/health-officials-scramble-to-pinpoint-mystery-illness-at-putnamville-prison