The lawyer for the House of Representatives asserted Wednesday that investigators looking into the financial dealings of then-Rep. Aaron Schock possibly committed a crime themselves when they directed a staffer-turned-informant to take materials from Schock’s district office.

In a letter to the U.S. attorney’s office that supervised the case, House General Counsel Thomas G. Hungar wrote that he had “serious concern” about investigators’ tactics, which he asserted the U.S. attorney’s office had “erroneously characterized as lawful.”

Requesting a staffer take records from a congressional office without authorization from the congressman or House clerk, Hungar wrote, “amounts to a solicitation of that employee to steal official records.”

[Did the Justice Dept. go too far in wiring a staffer to investigate a congressman?]

“Such conduct likely constitutes a federal crime, both on the part of the employee who steals the records and, quite possibly, on the part of the federal agents who induce the commission of that underlying crime,” Hungar wrote.

Defense attorneys for Schock, an Illinois Republican, had previously complained about how investigators used the informant in the case, though Hungar’s letter is in some ways more notable. It demonstrates that Congress as an institution — rather than just one charged legislator — feels that the Justice Department pushed the boundaries of its authority.

“I trust that your office and the Department of Justice have no interest in obtaining information by improper and potentially criminal and unconstitutional means, as appears to have occurred in this instance,” Hungar wrote. “I would appreciate your confirmation that my assumption is correct, and accordingly that steps will be taken to ensure that events like those described above will not occur in the future.”

A Justice Department spokesman declined to comment for this article.

Schock defense attorney George J. Terwilliger III said: “This letter is important because there needs to be accountability for the investigation and indictment in this case. There are legitimate questions about an investigation that only produced overblown allegations about administrative minutiae routinely addressed by the House of Representatives and the Federal Election Commission. If these are crimes, then every officeholder in Congress should feel at risk for indictment.”

Schock, whose Capitol Hill office was decorated in the style of the TV show “Downton Abbey” and whose six-pack abs landed him on the cover of Men’s Health magazine, was indicted last year on charges that he misspent government and campaign money for his personal benefit. He has asserted he is innocent and has waged a court battle with federal prosecutors.

[He’s got a ‘Downton Abbey’-inspired office, but Schock won’t talk about it]

Defense attorneys revealed last month that investigators had used a staffer-turned-informant — believed to be district office manager Bryan Rudolph — to surreptitiously record conversations in Schock’s district office and to gather materials. They said the informant took materials from other people — including travel-related receipts from another staffer’s desk drawer and thousands of emails from another staffer’s account — and they asserted his conduct was “improper — if not outright illegal.”

Prosecutors said the staffer had access to other people’s documents and email accounts as a part of his job, and they defended his conduct as legal. But they said they would nonetheless not use at trial the documents he turned over to investigators.

Hungar also complained about the staffer’s recording of conversations surreptitiously in a congressional office, which defense attorneys have alleged might run afoul of the Constitution’s provision that the executive branch not intrude into legislative activity. Hungar wrote that while surreptitious recording might be a legitimate law enforcement technique, it appeared the procedures investigators used in the Schock case did not “ensure compliance” with the Constitution.

Schock’s defense attorneys have filed motions asking a judge to dismiss the charges against Schock, and they have separately asked for more information on the use of the informant. Analysts have said, though, that even if a judge determines some misconduct occurred, dismissing the matter outright would be an extraordinary remedy. More likely, they said, the judge would bar prosecutors from using particular pieces of evidence at trial or come up with some other sanction.