The House Ethics Committee is investigating leaks around a now-closed investigation into Rep. Jim Costa, NOTUS has learned.

Last month, NOTUS first reported that the committee investigated Costa (D-California) in 2023 over allegations that he had made inappropriate advances toward two congressional interns. The case was dismissed and Costa has denied any wrongdoing.

The committee started sending letters to lawmakers who were members of the committee last Congress, inquiring whether they leaked information that NOTUS reported about the investigation, according to three sources familiar with the matter.

The effort to put lawmakers on notice for violating committee rules comes just weeks after the NOTUS story on the Costa probe.

A person who was in the room during the committee’s deliberations on Costa previously told NOTUS that some of the members had expressed concern about the congressman’s behavior. Now, according to another source, the committee is asking members who were present during those deliberations if they disclosed any information and telling them their responses must be provided under oath.

The committee has a long history of bipartisan announcements on matters it investigates — regularly issuing statements from both the chair and ranking member. It’s rare for the panel to accuse its own members of undermining its operations.

After joining the House Ethics Committee, members and staff swear an oath that they will “not disclose, to any person or entity outside the Committee on Ethics, any information received in the course of my service with the Committee.” Any “breaches of confidentiality shall be investigated by the Committee and appropriate action shall be taken,” according to the committee rules.

The rules do not specify what type of penalty leakers may be subject to. In 2009, the committee fired a staffer who had inadvertently placed confidential information on a publicly accessible computer network, The Washington Post reported at the time.

The House Ethics Committee declined to comment for this story.

Rep. Dave Joyce (R-Ohio), who was an Ethics Committee member last Congress, declined to say whether he had been contacted by the panel.

“Unlike other folks on there, I will not acknowledge whether I did or didn’t” receive a letter, Joyce told NOTUS.

The committee has come under scrutiny in recent months following the resignations of Reps. Eric Swalwell (D-California) and Tony Gonzales (R-Texas) in April over allegations of sexual misconduct. The committee had opened investigations into both lawmakers, but lost jurisdiction once they resigned.

Members of both parties have claimed the committee does not move fast enough to investigate allegations of wrongdoing by lawmakers. The Republican Women’s Caucus and the Democratic Women’s Caucus launched a task force aimed at providing recommendations by summer recess on how to overhaul the House Ethics process and how allegations are reported.

Rep. Michael Guest (R-Mississippi) told CNN in April that he is pushing for the committee to get more resources so it can move faster when conducting probes.