A former college football player with a history of mental illness allegedly gunned down three men at random near New Orleans — and is suspected in a fourth killing — and has been denied bail, authorities said.

Sean Barrette, a 22-year-old offensive lineman who played at the University of South Alabama and two other colleges, was remanded Tuesday on two counts of first-degree murder, one count of second-degree murder, three counts of attempted second-degree murder and other charges stemming from a string of shootings last month in Metairie and Kenner, NOLA.com reports.

Authorities in Jefferson Parish allege that Barrette killed Isai Cadalzo, 22, on June 17 in Metairie. Less than 24 hours later, Barrette, who had been committed to a mental institution as recently as April, allegedly killed Manuel Caronia, 45, and Nicky Robeau, 57, in seemingly indiscriminate shootings.

“We’ve not been able to identify any connection between the victims and the suspect,” Jefferson Parish Sheriff Joseph Lopinto told reporters last month. “I believe that he was actually picking his targets at random, shooting them in the vehicle.”

Barrette had twice been treated at mental health facilities dating back to December. A motive for the shootings remains unclear.

Barrette’s attorney, Paul Fleming, cited differing descriptions of the gunman by witnesses at one shooting scene in his request for bail, but Assistant District Attorney Kenneth Bordelon convinced a judge that the Metairie man is a “threat” to his community.

Investigators said ballistics evidence from the shooting scenes ties Barrette to the killings. Separately, Barrette is linked to bullet casings recovered at a fatal shooting in New Orleans on June 6 that claimed the life of 61-year-old Bruce Reed, as well as another shooting in the city a day earlier that left no one hurt, Lopinto told reporters last month.

Barrette, who was arrested at his parents’ home, was found in possession of a loaded .40-caliber pistol when he was taken into custody. Investigators also found receipts for ammunition that was shipped to the residence, AL.com reports.

After playing high school ball at John Curtis Christian School in New Orleans, Barrette played on the collegiate level at the University of South Alabama, Mississippi State University and Southeastern Louisiana University, according to AL.com, citing online records.

The daughter of one of the shooting victims, meanwhile, said Barrette wrecked her life in an instant, NOLA.com reports.

“He was our rock,” Nicole Robeau said of her father. “This just basically destroyed our life and took the most amazing man away from us.”

Barrette left Mississippi State to join the South Alabama Jaguars in 2016, but sat out that year’s fall semester due to the transfer, a University of South Alabama official who asked not to be identified told The Post early Thursday.

He then quit the team in February 2017 before ever playing a down, according to the school official.

“He never played in a game here,” the source said, adding that Barrette’s brief stint with the team was largely unremarkable.