PICKENS COUNTY, Ala. (WIAT)  — Glenn Foster, a former professional football player with the New Orleans Saints, died Monday in Alabama after he was taken into custody over the weekend, authorities said. He was 31.

Foster was booked Sunday on charges of assault and third-degree robbery, Pickens County Sheriff’s Office records show.

NewsNation affiliate WIAT reports that Foster was taken to a local hospital Monday, where he later died. A cause of death had not been released as of Tuesday. The Alabama Law Enforcement Agency has begun an investigation into Foster’s death, sharing this statement with NewsNation affiliate WGNO:

“On Monday, Dec. 6, at the request of the Pickens County Sheriff’s Office, Special Agents with the Alabama Law Enforcement Agency’s (ALEA) State Bureau of Investigation (SBI) are investigating an in-custody death, which was reported on Monday, Dec. 6, at a medical facility in Northport. SBI Special Agents identified Glenn Foster, 31, of Louisiana as the deceased. The body was released to the Alabama Department of Forensic Sciences for further investigation. Nothing further is available as the investigation is ongoing. Once complete, the findings will be turned over to the Tuscaloosa County District Attorney’s Office.”

Foster, an Illinois native, played football at the University of Illinois before signing with the Saints in 2013 as an undrafted free agent. He would play in 12 games that season and record three sacks and eight tackles. Foster would play just five games in 2014 before being released from the team.

He officially retired from the NFL in 2016.

Rep. Kam Buckner, a state lawmaker for Illinois, posted a tribute to Foster on Twitter, saying “No words right now. Rest Powerfully, Little Brother.”

Local reports say Foster worked as a contractor, developer and real estate agent in Louisiana after leaving the NFL.