Federal prosecutors late Friday filed one count of conspiracy to commit bribery against Commonwealth Edison’s former chief lobbyist, a one-time powerhouse in Springfield whom Speaker Michael Madigan invited as his personal guest to House inauguration festivities last year.

Named in the four-page federal filing was Fidel Marquez, ComEd’s former senior vice president of governmental and external affairs from 2012 until his abrupt and unexplained departure from the company last September.

The specific kind of court filing naming Marquez is indicative of a likely guilty plea and is a clear tightening of the federal probe into potential wrongdoing by the longest-serving House speaker in American history.

Documents obtained Friday by WBEZ through an open-records request to the speaker’s office showed that Madigan issued a personal invitation to Marquez to attend January 2019 House inauguration ceremonies as the speaker’s guest, underscoring the close personal relationship between the two.

Late Friday, U.S. Attorney John Lausch’s office alleged that Marquez funneled a payment of $37,500 to an unnamed company, which in turn was expected to spread “a substantial portion” to associates of Madigan, who was referred to as “Public Official A” multiple times in the filing.

Prosecutors also alleged that Marquez and ComEd illegally doled out jobs, contracts and cash payments to Madigan’s political allies who “performed little or no work that they were purportedly hired to perform for ComEd.”

The bombshell filing indisputably brings the federal corruption scandal into ComEd’s lobbying practices ever closer to the Southwest Side Democrat and comes days ahead of the opening of a special House investigation into Madigan’s conduct. The Republican-driven inquiry that could ultimately lead to sanctions against the speaker.

Last month, federal investigators subpoenaed Madigan’s state office, seeking records involving AT&T, Walgreens, Rush University Medical Center and a host of political operatives and lobbyists.

On Thursday, Madigan issued a denial of wrongdoing after Republicans launched a series of investigative hearings against him in the House. The speaker specifically disputed the contention that he helped ComEd favorably navigate its way through the statehouse in exchange for jobs and contracts for his allies.

“As I have stated previously, I have never made a legislative decision with improper motives. The notion that the passage of two consequential pieces of energy legislation was tied to the hiring or retention of a few individuals is seriously mistaken,” said the speaker, who has not been charged.

In July, ComEd was charged with bribery and admitted it steered jobs and contracts to Madigan’s political allies. The speaker is also identified in that document as “Public Official A,” and Marquez is identified as “Senior Executive 1,” WBEZ has confirmed.

According to prosecutors, Marquez worked with former ComEd CEO Ann Pramaggiore to funnel about $5,000 a month to former Chicago Ald. Michael Zalewski, a Madigan ally. They say Pramaggiore referred to the speaker’s list of requested patronage hires as “the roster.”

Neither Zalewski nor Pramaggiore have been charged with wrongdoing.