Federal investigators last week subpoenaed Commonwealth Edison for “records of any communications” the power company had with powerful Democratic state Sen. Martin Sandoval, the Better Government Association and WBEZ have found.

In a filing Friday with regulators, Chicago-based ComEd and its parent company, Exelon Corp., disclosed receiving the subpoena that same day from federal prosecutors in Chicago. According to the filing, ComEd officials said authorities sought all of the utility giant’s communications with other, unnamed “individuals and entities.”

It’s the second subpoena ComEd has received this year in the wide-ranging federal corruption probe. It came 10 days after investigators served search warrants at Sandoval’s offices at the state Capitol in Springfield and in Cicero, where FBI agents carried out computers and boxes of documents.

In the initial subpoena this spring, ComEd — which enjoys a monopoly for providing electricity for much of northern Illinois — said the U.S. attorney’s office asked executives to turn over “information concerning lobbying activities in the state of Illinois.”

WBEZ and the BGA first reported in July that investigators also had searched the home of former Chicago Ald. Michael Zalewski, as the feds looked into alleged efforts to get work for Zalewski at ComEd.

Three sources familiar with the federal probe said it centers at least partly on interactions between Zalewski, Illinois House Speaker and Democratic Party Chairman Michael Madigan and Michael McClain, a longtime ComEd lobbyist and Madigan confidant.

Around the same time as the search of Zalewski’s home, authorities also contacted McClain and Kevin Quinn, a veteran Madigan political operative whose brother is alderman of the speaker’s 13th Ward power base, on the Southwest Side of Chicago.

But until the disclosure of the most recent subpoena sent to ComEd, it was not publicly known that those aspects of the sprawling federal probe had any connection to the investigators’ interest in Sandoval, one of the most influential lawmakers in Illinois.

The senator’s daughter, Angie Sandoval, is a longtime employee of ComEd, according to her online networking profile.

On LinkedIn, Sandoval says she was promoted in June to “Senior Account Manager” in ComEd’s “Government & External Affairs” department. She had started working for ComEd in 2013, as an associate manager for “National Accounts” based in Oak Brook, and in 2017, she became a “business analyst” under ComEd’s senior vice president for government and external affairs.

Sandoval has not been charged with any crime. His lawyer, Craig Tobin, could not be reached for comment Thursday.“

In the filing Friday with the U.S. Securities and Exchange Commission, ComEd and Exelon said, “The companies have cooperated fully with the U.S. attorney and intend to continue to cooperate fully and expeditiously with any government requests of inquiries.”

ComEd and Exelon also told the SEC last week that they had formed a “special oversight committee” in June, after the first subpoena from U.S. Atty. John Lausch’s office. The committee’s purpose is “to oversee the companies’ compliance with the subpoena, any further action taken by the U.S. attorney and any resulting actions that may be required or recommended.”

The committee hired an “independent outside counsel,” according to the disclosure document, but the ComEd spokeswoman would not say who that lawyer is.

The long list list of ComEd lobbyists in Springfield reads like a who’s who of former Madigan aides and retired lawmakers from the speaker’s House Democratic caucus. Among them are Michael Kasper, Madigan’s longtime lawyer, and Will Cousineau, who was political director for the speaker and the state party for eight years.

As for Sandoval, FBI agents went to his two government offices and his home on Sept. 24, sparking a week of federal activity across the Chicago area. That included searches of a politically connected asphalt company in Bartlett and the municipal offices of southwest suburban Lyons and McCook — two communities in Sandoval’s Senate district.

But it is not yet known exactly what investigators want to know about Sandoval. In response to open-records requests from news organizations, Illinois Senate President John Cullerton, D-Chicago, has blacked out much of the information from copies of the search warrant served at Sandoval’s offices. WBEZ is suing the state Senate for unredacted copies of those documents, which are commonly made public under the state’s Freedom of Information Act.

The federal scrutiny of Sandoval has divided many of the top Democrats in Illinois, with first-term Gov. JB Pritzker calling for his removal as chairman of the influential Senate Transportation Committee, while Cullerton and other top senators are standing by the often-outspoken Sandoval.

Sandoval was first elected to Springfield in 2003 with the help of the Hispanic Democratic Organization, a corrupt patronage army formed to support then-Chicago Mayor Richard M. Daley and his allies in City Council and state legislative campaigns.

In August, Sandoval drew national criticism after a man who attended his political fundraiser was photographed acting out a mock execution of President Donald Trump.

Dan Mihalopoulos is an investigative reporter on WBEZ’s Government & Politics Team.