3:21 PM PT -- Foster was initially arrested around midnight on Dec. 4 ... after cops say he led officers on a wild police chase.
Reform Police Department chief Richard Black tells TMZ Sports ... an officer clocked Foster going 92 MPH in a 45 MPH zone -- but when the cop tried to stop Foster, Black says the former football player took off.
According to Black, Foster evaded cops for roughly 8 miles, driving into the nearby town of Gordo ... where Black says cops eventually deployed spike strips to get him to slow down.
Black says Foster was ultimately taken into custody there -- though Black says he was "uncooperative," adding that cops did have to wrestle him to the ground in order to get the cuffs on him.
Black says Foster was booked into the county jail on Saturday -- but he said it was unclear exactly what happened to the former New Orleans Saints defensive lineman after he arrived.
1:22 PM PT -- Law enforcement officials in Alabama tell TMZ Sports ... Foster did die on Dec. 6 while in custody. They added an investigation is underway and "nothing further is available" at this time.
Former NFL defensive lineman Glenn Foster -- who logged three sacks for the New Orleans Saints in 2013 -- has reportedly died ... just two days after he was arrested in Alabama.
He was 31 years old.
A Pickens County Medical Examiner official confirmed the Dec. 6 death, according to NOLA.com, though the spokesperson would not reveal the circumstances surrounding the passing, saying an investigation is currently underway.
Jail records show Foster was arrested and booked on Dec. 4 on charges of reckless endangerment, resisting arrest and attempting to elude. The records show he was later rebooked on Dec. 5 on charges of simple assault and robbery.
It's unclear if Foster was still in police custody at the time of his death -- we've reached out to the Pickens County Sheriff's Office for comment, but it said the Alabama State Bureau of Investigation is handling inquiries.
Multiple attempts to reach spokespersons for the Alabama SBI have been unsuccessful.
Foster -- who starred for the Univ. of Illinois -- signed with the Saints as an undrafted free agent in 2013 and played two seasons for the team, recording 8 tackles in 17 games.
He retired from the league in 2016.
I really can’t find the words to properly express 😔. Rest In Peace Glenn Foster, you’ll be missed bro! 🙏🏾💙
Foster's former Saints teammate, current New Orleans star Terron Armstead, commented on the news on Tuesday -- saying on his Twitter page, "I really can't find the words to properly express. Rest In Peace Glenn Foster, you’ll be missed bro!"