The U.S. Department of Justice is investigating Aaron Schock the Illinois Representative over his business deals and congressional expenses. FBI agents started to issue subpoenas to a person who is familiar with his case, witnesses and others said a news agency on Friday.

Investigators were putting their focus on the House office expenses for Schock, expenditures by his campaign for re-election and personal investments of his with political donors.

Schock is just 33 and described as a young Republican who is media savvy. However, on Tuesday, he abruptly resigned from office weeks after mounting media reports over personal finances and questionable expenditures.

The government has convened a grand jury in Springfield, Illinois, said a person close to the event, but who is not authorized to discuss the case publicly.

That person said that agents from the FBI were seeing people that were close to the congressman who due to subpoena had to testify. The grand jury would hear testimony starting in the early part of April. A spokesperson and an attorney for Schock did not release any comments when contacted.

The sudden resignation of Schock followed revelations about business deals of his, the lavish spending, personal millage reimbursements, office redecorating and travel.

Investigators in Congressional ethics had started probing the conduct of Schock prior to his resignation announcement, but the probe was expected to shut down due to the federal investigation.

Questions have included investigations into the real estate transactions of Schock, as well as entertainment expenses and air travel, which include some events that he documented with photographs on Instagram.

This past week it was confirmed the Office of Congressional Ethics reached out to associates of Schock as a way to get the process started.

An air charter service owner in Peoria confirmed on Friday Schock’s extended flights on planes campaign donors owned.

Usually House ethics investigators will stop inquiries once authorities from the federal government open a probe or when orders from the House Ethics Committee say to halt one.