Former U.S. House Speaker Dennis Hastert agreed to pay $3.5 million to a man he allegedly sexually abused when the victim was 14, prosecutors in Chicago said in a court filing Friday.

The filing was the first time in the hush-money investigation into Hastert’s past that prosecutors clearly stated that the former Illinois Republican lawmaker had paid money to the unidentified victim. It also included allegations from four men who said Hastert sexually abused them when they were students at the high school where he taught and coached wrestling in the 1970s.

Investigators learned of the hush-money agreement that Hastert, now 74, had with the victim after looking into a string of suspicious bank withdrawals he had made over more than four years. Investigators wondered whether Hastert was being extorted or whether he was making illegal payments related to his work as a lobbyist after leaving Congress.

“The answer, as it turned out, after a lengthy investigation, was neither of these things,” the court filing said. “The actual purpose of the withdrawals was to pay an agreed-upon total of $3.5 million to compensate [the victim].”

The alleged sexual abuse occurred in the 1970s when Hastert worked at a high school in Yorkville, Illinois, west of Chicago. Three of the four male accusers were wrestlers, including the one who was being paid hush money, and one was a student team manager. Two say Hastert performed sexual acts on them when they were 14 and 17 years old, the Associated Press reported.

Hastert pleaded guilty in October to breaking banking laws for the way he tried to mask his large hush-money payment by making multiple small withdrawals. Though the statute of limitations has run out on the sexual assault allegations, Hastert faces up to six months in prison for his financial crime. His sentencing hearing is scheduled for April 27.

Hastert served as a Republican in the House of Representatives for 20 years after first being elected in 1986. He became speaker, replacing Newt Gingrich, at the beginning of 1999, serving until the Democrats captured the House in the 2006 elections. Later in 2007, he quit to become a lobbyist.