CHICAGO – For months, federal authorities have hinted at the motive behind the hush-money payments former U.S. House Speaker Dennis Hastert has admitted to making: the sexual abuse of a teenage boy when Hastert was still a suburban high school teacher and wrestling coach.

But now, a Tribune investigation has uncovered new details of the case — at least four people have made what law enforcement sources say are credible allegations of sexual abuse against Hastert.

The Tribune has determined the identities of three of them, all men, whose allegations stretch over a decade when they were teenagers and Hastert was their coach. One is dead. The Tribune has approached the other two — described in federal court records as Individuals A and D — and confirmed their roles in the case.

The man who received $1.7 million from Hastert and is at the center of the federal indictment — Individual A — declined to be interviewed by the Tribune. Behind the government's carefully worded court documents, reporters discovered a sometimes-pained narrative of his life since his days as a standout wrestler in the 1970s and how his interactions with Hastert might have affected him.

Individual D has talked to the Tribune at length but has not agreed to be named, although he is considering speaking at Hastert's sentencing in federal court April 27. The Tribune typically does not name victims of alleged sexual abuse without their consent.

Hastert is alleged to have sexually abused the teens identified by the Tribune when he was a teacher and coach at Yorkville High School in Chicago's far southwest suburbs, decades before he became the longest-serving Republican speaker. Some of the alleged conduct, which prosecutors have not detailed, might come to light this week when prosecutors are expected to file sentencing memorandums.

Most in town would come to know "Denny," as he was most frequently called, as the man who put Yorkville on the map by winning a 1976 state wrestling championship and bringing several other squads close to a state title.

One of the alleged victims served as a team equipment manager a few years after Hastert arrived at the school in 1965. Stephen Reinboldt died of AIDS in 1995, and his younger sister has long spoken out about the details she said he shared with her while alive. Two others, who came to the school later, were talented and popular student-athletes from well-known local families — the sort of combination that often bodes well for the future. They all graduated from college. The identity of the fourth accuser whom authorities have deemed credible remains unknown.

Hastert attorney Tom Green did not specify any sexual abuse by his client but did say Hastert was apologetic and had suffered humiliation and shame. "Mr. Hastert has made mistakes in judgment and committed transgressions for which he is profoundly sorry," Green said. "He fully understands the gravity of his misconduct decades ago and regrets that he resorted to an effort to prevent the disclosure of that misconduct."

In a small town where the Tastee Freez was a gathering place for teens, Hastert taught many siblings of the alleged victims and knew most of their parents on a first-name basis. Each of the alleged victims identified by the Tribune had their struggles. Yet they all kept quiet about their hometown's favorite son and the inappropriate sexual contact that they alleged he had with them.

Now 74 and said to be in failing health after suffering a near-fatal blood infection and stroke, Hastert has not been charged with harming a child. Such charges, according to legal experts, would be barred by statutes of limitation. Instead, Hastert pleaded guilty last year to illegally structuring cash withdrawals to evade bank currency-reporting requirements as he pooled his money to give to Individual A — who has known Hastert much of his life as a relative of one of the retired congressman's friends — as part of an agreement to keep him quiet.

Tribune reporters spent 10 months contacting scores of athletes and students coached and taught by Hastert.

Jolene Burdge said her brother Stephen Reinboldt confided to her in 1980 that Hastert had sexual contact with him all through high school. Reinboldt, who graduated in 1971, was an equipment manager for the school's wresting and football teams.

A former classmate also confirmed the account.

Burdge said her brother saw Hastert as a mentor. Hastert was about 11 years older, still single and had been teaching a few years. Hastert married his wife of more than 40 years, Jean, two years after Reinboldt graduated.

Burdge will stand before Hastert to read a victim-impact statement.

The alleged misconduct against Individual D would have occurred late in the coach's tenure at Yorkville. Individual D was a popular student and good athlete. He grew up to marry, have children and become a successful businessman.

With the sentencing hearing looming, a source said Hastert called one of Individual D's relatives, hoping to get a letter to show Hastert had done good things in an effort to get a more lenient sentence.

Individual D then made a call of his own. He told authorities he would prepare a statement to be used in court detailing what Hastert did to him.