NATCHEZ — The family of a guard killed during last year’s prison riot in Adams County filed a federal lawsuit Wednesday blaming inadequate staffing and poor treatment for creating a dangerous environment at the facility.

Corrections officer Catlin Carithers was beaten to death during the May 20, 2012, riot at the privately run Adams County Correctional Facility east of Natchez. It took hours for authorities to control the riot, which grew to involve hundreds of inmates and injured at least 20 people.

The lawsuit was filed in U.S. District Court in Natchez against Nashville, Tenn.-based Corrections Corporation of America, which runs the prison.

Carithers’ family declined to comment on the lawsuit Wednesday.

In a statement CCA spokesman Steven Owen said the company “takes the safety and well-being of our staff very seriously, and we work diligently to provide our dedicated correctional officers, chaplains, nurses and teachers the training, security and support systems they need in this very challenging field.

“In addition to conducting our own thorough review, we have cooperated fully with law enforcement throughout their investigation of the incident, and we support full prosecution of those inmates responsible for this disturbance,” Owen said.

The lawsuit, which seeks unspecified damages, alleges CCA “created a dangerous atmosphere for the correction officers by depriving inmates of basic needs and treating them inhumanely.”

The family’s lawsuit also alleges prison officials were told by an informant in the days before the riot that the situation was becoming volatile and that the officials failed to warn Carithers that he and other guards were on an inmate “hit list.”

Carithers was off the day of the riot but was called in to help, his family has said.

The prison houses nearly 2,500 inmates convicted of crimes while being in the U.S. illegally.

FBI investigators alleged in court records that the riot was started by a group of Mexican inmates, known as Paisas, who were angry about what they considered poor food and medical care and disrespectful guards. Paisas are a loosely affiliated group within the prison, without ties to organized gangs, FBI spokeswoman Deborah Madden has said.

Several inmates have been charged with rioting in the case. One of them, Marco Perez-Serrano, has been identified as the first person to attack Carithers with a food tray.

A complaint filed by an FBI agent says prisoners took food service carts out of the dining hall and kitchen and stacked them on top of each other to climb onto the roof, where Carithers was working.

Carithers, a Franklin County High School graduate, joined CCA in 2009.

His cousin, Jason Clark, told The Associated Press in an interview after the riot that Carithers was engaged to be married and was excited about a recent promotion that took him off weekend shifts.

He had been trained in recent years as part of the prison’s special response team and was called to help with the uprising, Clark said at the time.

The prison’s special response team and the Mississippi Highway Patrol’s SWAT team worked to end the riot while state and area law enforcement officers, some from neighboring Louisiana, helped secure the outside perimeter of the prison.