Former Republican Rep. Dennis Hastert, who was the longest-serving GOP House Speaker, died on Monday at the age of 84.

Hastert died peacefully of natural causes at his home, according to Kendall County Coroner Jacquie Purcell. The longtime politician represented Illinois' 14th Congressional district for 20 years and served as Speaker of the House for eight years before retiring in 2007.

His career was later tarnished by a bank fraud conviction linked to his efforts to quash the story of a former student who accused him of sexual abuse during his time as a high school wrestling coach. He was sentenced to 15 months in prison in 2016.

Hastert also underwent sex offender treatment, two years of supervised release after his time behind bars and paid a $250,000 fine to a crime victims fund.

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Hastert pleaded guilty in the case to attempting to pay $3.5 million to an unnamed individual to keep the alleged sexual abuse a secret.

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Before he sentenced Hastert, Judge Thomas M. Durkin described the then-74-year-old Illinois Republican as a "serial child molester," and that "accusing Individual A of extorting you was unconscionable."

Multiple alleged victims and their family members read victim impact statements prior to Hastert's sentencing.

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Assistant U.S. Attorney Steven Block called Hastert's conduct "horrendous." But because of the statute of limitations, Hastert could only be charged with a financial crime related to the payments he was making to one of at least four victims of sexual abuse.

Block said the sentence should take into account that Hastert "continues to deny what should now be obvious to everyone," that the payments were to conceal sexual abuse.

Defense attorney Thomas Green said he "acknowledges and respects" the pain of the man who described being molested as a teenager. He urged the judge to take into consideration the "entire arc" of Hastert's life, asserting that he reshaped his life as a public servant during his political career.

The Associated Press contributed to this report.