A football star, a teacher and — a heroin dealer?

Brian Thurman was a college football player who went on to become a teacher in the northwest suburbs, but at the same time he was working with kids he was a heroin dealer, federal officials said Wednesday.

Thurman, 44, is on trial this week in U.S. District Court, facing charges that he sold heroin to a government informant in Thurman’s home in the Austin neighborhood on the West Side. He also allegedly possessed illegal handguns, including one he bought from a former downstate volunteer cop.

In the 1990s, Thurman was a defensive back for Purdue University after a stellar football career at the former Weber High School on Chicago’s Northwest Side. He was briefly in the Canadian football league and the NFL, according to news reports.

At the time of his arrest in 2013, Thurman was the dean of discipline for Joseph Academy, a Des Plaines charter school for children with learning disabilities, federal authorities said. School officials didn’t return calls seeking comment.

Thurman’s current legal problems began when a drug dealer was stopped with heroin in a spare tire in the trunk of his car in Duluth, Minnesota, on Aug. 6, 2013.

The dealer, Courtney Williams, fingered Thurman as his source and became an informant for the government, officials said.

The police in Duluth worked with ATF agents in Chicago to investigate Thurman. At their request, Williams drove to Chicago on Aug. 10, 2013, and met Thurman in his basement. Their meeting was recorded by a hidden device.

During the meeting, Williams paid Thurman $10,000 for the heroin he allegedly bought from Thurman days earlier, prosecutors said. Thurman was secretly recorded talking about diluting heroin with additives, authorities said.

On Sept. 23, 2013, Williams returned to Chicago and bought about 150 grams of heroin from Thurman, prosecutors said. He paid Williams with cash the ATF provided him, according to the government.

Before the alleged deal, Williams texted Thurman “150,” meaning he wanted 150 grams of heroin, prosecutors said. Thurman responded: “Yeap.”

Afterward, federal agents stormed Thurman’s house and arrested him in his basement office.

ATF agents recovered two illegal handguns, a .40-caliber Glock and a .380-caliber Bryco Arms, from Thurman’s home, prosecutors said.

The government is accusing Thurman of running a heroin-trafficking business from his basement.

“Obviously, we feel betrayed that a former law-enforcement officer would be selling a gun illegally,” said Thomas Ahern, a spokesman for the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives.

“We find it incredibly disheartening that a teacher would do this. We need teachers to partner with law enforcement to keep kids away from drugs and violence.”

But Thurman’s attorney, Andrea Gambino, said, “What Brian Thurman is not is a drug dealer.”

Gambino said the government’s informant — Williams — was facing a potential sentence of at least 10 years in prison and framed Thurman to save his own neck.

Gambino said the Sept. 23, 2013, deal didn’t add up.

Authorities have recovered only about half of the $25,000 in marked currency they gave Williams to buy heroin from Thurman on that day, she pointed out.

Christopher Labno, an ATF agent, acknowledged in his testimony Wednesday that agents found only $12,500 of the marked cash in Thurman’s home. About $27,000 in unmarked bills were discovered in a safe, Labno said.

In his testimony, Labno said Thurman said he would cooperate with the ATF after he was arrested, but he refused to sign anything.

Thurman allegedly gave up the name of his drug supplier and admitted he sold heroin to Williams, Labno said. But Thurman later refused to cooperate with the ATF.

Thurman’s cousin, Stephen Taylor, testified Wednesday that he sold the .40-caliber Glock pistol that ATF agents recovered from Thurman’s basement.

Taylor said he bought the gun when he was a volunteer police officer for the Bourbonnais Police Department. Then he moved to Oak Park and was going through financial problems, so he asked Thurman if he wanted to buy the gun, Taylor testified.

Thurman gave Taylor $350 in cash for the gun, Taylor said. He admitted that he didn’t follow the legal procedures to transfer the weapon to his cousin.