Former Illinois Gov. James R. Thompson, known as “Big Jim” during a long career that eventually made him the state’s longest-serving chief executive, has died. He was 84.

Thompson died shortly after 8 p.m. Friday at the Shirley Ryan AbilityLab in Chicago, his wife, Jayne, told the Chicago Tribune and the Chicago Sun-Times. The Tribune, citing a police report, reported Thompson had been recovering there for several weeks after suffering heart problems.

“It was very sudden,” Jayne Thompson told the Tribune. “I was told that his heart simply stopped.”

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James Thompson, a Republican from Chicago, was first elected in 1976 and eventually served four terms before leaving office in 1991. A moderate, he managed the state through recession years in the 1980s. He also helped put together a plan to help the Chicago White Sox get a new stadium to head off a potential move out of state.

Widely respected across the state, Thompson was honored in 1993 when the state government building in downtown Chicago was named after him.

FILE - In this Aug. 21, 2007 file photo, former Illinois Gov. Jim Thompson, pauses before beginning a news conference in Chicago. Thompson, known as “Big Jim” during a long career that eventually made him the state's longest-serving chief executive, has died. He was 84. Thompson died Friday, Aug. 14, 2020 at the Shirley Ryan AbilityLab in Chicago, his wife, Jayne, told the Chicago Tribune and the Chicago Sun-Times. (AP Photo/M. Spencer Green, File)

FILE - In this Aug. 21, 2007 file photo, former Illinois Gov. Jim Thompson, pauses before beginning a news conference in Chicago. Thompson, known as “Big Jim” during a long career that eventually made him the state's longest-serving chief executive, has died. He was 84. Thompson died Friday, Aug. 14, 2020 at the Shirley Ryan AbilityLab in Chicago, his wife, Jayne, told the Chicago Tribune and the Chicago Sun-Times. (AP Photo/M. Spencer Green, File)

“As the longest-serving governor in Illinois history, ‘Big Jim’ was known to treat people he encountered with kindness and decency,” Democratic Gov. J.B. Pritzker said in a statement Saturday. “Jim dedicated himself to building positive change for Illinois, and he set an example for public service of which Illinoisans should be proud. He will be remembered and revered as one of the titans in the history of state government.”

“He was a great guy, no question about that,” said Republican former Gov. George Ryan, a longtime friend. “He did a lot of good things for Illinois.”

After he left public office, Thompson served as a member of the National Commission on Terrorist Attacks Upon the United States to examine the Sept. 11, 2001, attacks.

Before becoming governor, Thompson rose to prominence as a prosecutor, working in the Cook County State’s Attorney’s Office and later as a U.S. attorney.

In the early 1960s, he prosecuted Lenny Bruce after the comedian held up a photograph of a woman’s breast while on stage at a Chicago nightclub.

After he was appointed U.S. attorney for the northern Illinois district by President Richard Nixon, Thompson became known for anti-corruption cases, including the prosecution of Democratic former Gov. Otto Kerner Jr., by then a federal appeals judge.

Thompson and his staff uncovered massive voter fraud in 1972, an effort that led to 83 indictments and 66 convictions or guilty pleas. He headed the prosecution that led to the conviction of a powerful Chicago alderman and took part in the investigation of Republican Vice President Spiro T. Agnew, who eventually pleaded no contest to tax evasion.

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But Thompson also made headlines when, as a leader of the law firm Winston & Strawn, he agreed to defend Ryan on a pro bono basis in a corruption case that eventually landed Ryan in prison. In a 2015 article when Thompson’s retirement from the firm after a quarter century was announced, Crain’s Chicago Business noted that Thompson’s decision to represent his fellow former governor without receiving payment ultimately cost the firm more than $10 million.