Ex-House Speaker Dennis Hastert had been paying someone to cover up sexual misconduct before he was indicted for allegedly concealing those payments, a law enforcement source told Fox News Friday.

The source told Fox that the bank withdrawals that led to Hastert's indictment relate to an attempted cover up of sexual misconduct by the former Illinois congressman during his time as a high school teacher and wrestling coach in Yorkville, Ill.

The Los Angeles Times reported Friday, in one of the first accounts of the alleged cover up, that the other individual involved was male.

It also later reported that a top official said investigators also spoke with a second person, not being paid by Hastert, who raised similar allegations that would corroborate the initial account.

"It goes back a long way, back to then," an official earlier told the paper. On why the former Republican House speaker was making the payments, the source said it was to cover up his past relationship with the man.

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"It was sex,'' the source told the newspaper. Another official reportedly said it involved sexual abuse.

The federal indictment said only that Hastert had been hiding payments he made in order to compensate for and conceal "prior misconduct."

It said he agreed to provide $3.5 million to someone described only as "Individual A." It did not elaborate on the alleged misconduct or indicate if Individual A is a man or a woman. However, it said the person has known Hastert most of the individual's life. It also said the person has been a resident of Yorkville, Ill.

The 73-year-old Illinois Republican is specifically accused of structuring the withdrawal of $925,000 in cash in order to evade the requirement that banks report cash transactions over $10,000. He is also accused of lying to the FBI about the withdrawals.

The former congressman was indicted on two counts, both carrying a maximum penalty of five years in prison and a $250,000 fine.

Amid the charges, Hastert resigned from his job at the Washington firm of Dickstein-Shapiro LLP, where he was a lobbyist for the tobacco industry, among other interests. The resignation was confirmed by a firm spokesman and his bio has been removed from the firm's website.

Speculation, meanwhile, was running high on Friday regarding the person behind the alleged blackmail.

A C-SPAN clip that surfaced from a 2014 "Washington Journal" segment fanned the flames. It showed Hastert responding to a caller identified as "Bruce."

The caller greets Hastert and then says, "Remember me from Yorkville?" He then laughs and hangs up.

The indictment said the misconduct in question began "years earlier" and seemed to suggest it was back in his teaching days, introducing Hastert from the outset as having worked as "a high school teacher and coach in Yorkville, Illinois," from 1965 to 1981.

Hastert was first elected to Congress in 1987 to represent an Illinois district west of Chicago, then became speaker when Newt Gingrich stepped down from the post in 1999. He held that office until 2007 after a bitter defeat for Republicans in the 2006 midterm elections. He went on to a successful lobbying career.

But as the indictment charges lay out, Hastert allegedly began meeting with the unnamed individual in 2010 and agreed to pay $3.5 million. He allegedly began withdrawing large sums to make the payments totaling more than $1 million through 2012, drawing the attention of the feds.

According to The Washington Post, Hastert made most of his money during and after Congress. He came to Washington with a net worth of no more than $270,000, according to the paper, but left office in 2007 with between $4 million and $17 million, mostly in real estate holdings. He has been married to Jean Hastert since 1973, and they have two children, Ethan and Joshua. Hastert also reportedly suffers from diabetes and requires daily insulin shots.

The Associated Press contributed to this report.