For the second time in three days, federal agents Thursday hit government offices around Chicago as part of an ongoing criminal investigation, this time swooping down on three southwest suburban villages that have historically drawn the feds’ interest.

Agents visited McCook village hall — where Cook County Commissioner Jeff Tobolski is mayor — as well as the village halls in Lyons and Summit. They also visited Getty Insurance in Lyons, the agency of Lyons Mayor Christopher Getty.

The burst of federal activity was related to Tuesday’s raid on the home and offices of Democratic state Sen. Martin Sandoval, according to a source. And it was the latest public display in what appears to be an aggressive campaign by the feds against political corruption in Illinois.

An FBI spokesman described the visit to McCook, Lyons and the insurance agency as “authorized law enforcement activity,” but he drew a distinction in Summit, calling the visit there “investigative activity.” FBI agents took no records in Summit but interviewed village employees about contracts and licensing, a source said.

Meanwhile, in McCook, sources said agents arrived shortly before offices opened for the day and left hours later, carrying boxes of documents and computer equipment — a scene that’s become all too familiar in recent months.

The feds’ latest activity also involves agents from IRS Criminal Investigation.

McCook village attorney Gary Perlman confirmed a search warrant had been executed Thursday, but he declined to provide a copy. He said investigators were seeking information related to “various contractors that have done work with the village.”

“We’re still looking at it ourselves,” Perlman said.

Phone calls to Tobolski’s offices went directly to voicemail. He did not attend Thursday’s Cook County Board of Commissioners meeting — Board President Toni Preckwinkle said he was sick — and his wife hung up on a reporter when asked by phone about contact with federal authorities.

Still, Tobolski’s offices treated commissioners and staff to Buona Beef on Thursday in a belated celebration of his birthday.

It’s unclear whether the investigation is tied to Tobolski. His wife, Cathleen, is her husband’s campaign treasurer. His brother, Theron, is McCook’s treasurer. He told the Sun-Times he didn’t know what the raid was about.

“I have no idea what it’s over,” Theron Tobolski said. He said he didn’t know if his brother was a target.

“I honestly have no idea,” he said.

Carlos Aparicio, a lawyer on Jeff Tobolski’s Cook County staff, said federal agents hadn’t visited Tobolski’s county offices. And news of the raid in the suburbs slowly made its way to other commissioners.

“I had no idea — you just broke the news to me,” Commissioner Stanley Moore, D-Chicago, said Thursday afternoon. “I’m surprised. Nobody wants anything bad to happen to anybody.”

Lyons officials did not immediately return phone calls requesting comment.

Jeff Tobolski has faced criticism over the years for his hiring practices in the tiny town of McCook, which has about 200 people. He has hired numerous family members for village jobs. In 2010, he also hired one of his political volunteers and an ex-Cook County employee who pleaded guilty in 2007 to official misconduct and bribery for conning a woman into a sex act in return for a nonexistent government job. The man, Felice “Phil” Vanaria, got a part-time job at the village-owned indoor gym.

The latest move by the feds came two days after federal agents executed search warrants on the Southwest Side home and Cicero and Springfield offices of Sandoval. The Chicago Democrat’s district includes parts of Summit, McCook and Lyons.

Gov. J.B. Pritzker’s office said the governor is concerned about the reports of federal activity.

“No elected official in Illinois should use their office to personally profit, and these reports are deeply concerning to the governor,” said spokeswoman Emily Bittner. “The governor expects elected officials to uphold the highest ethical standards, and for anyone who fails, they should be held accountable to the fullest extent possible.”

But federal investigators also appear to be conducting multiple ongoing probes of public officials in Chicago and other parts of Illinois. Records show the feds have spent years laying the groundwork, but it all roared into the public’s attention when the FBI last November raided the City Hall office of Ald. Edward M. Burke (14th). Burke has since been hit with a 59-page racketeering indictment. Former Ald. Danny Solis (25th) has also been outed as a cooperator who secretly recorded Burke.

The feds in June also raided the offices of Ald. Carrie Austin (34th), though she has not been charged with any wrongdoing.

State Sen. Thomas Cullerton found himself under indictment in August. Associates of Illinois House Speaker Mike Madigan, including former Ald. Mike Zalewski (23rd), have also been circled by the feds in recent months. And ComEd has acknowledged a subpoena targeting its lobbying activities.

Contributing: Tom Schuba