The Department of Justice has become involved in a corruption investigation focused on individuals at Oslo-listed oil and gas exploration and production company PetroNor that has grown to include its U.S. citizen chairman of the board.

Eyas Alhomouz has been named a suspect in an ongoing probe by the National Authority for Investigation and Prosecution of Economic and Environmental Crime (Økokrim) in Norway, PetroNor announced Monday. Økokrim shared information regarding Alhomouz with the Justice Department, which has launched its own, separate investigation, according to the company.

No further details were shared regarding the Justice Department’s involvement.

Økokrim in December detained former PetroNor Chief Executive Knut Søvold on suspicion of criminal offenses. The company named Jens Pace as interim CEO.

No charges have been announced against PetroNor or its subsidiaries, the company noted.

Still, the company has implemented a handful of remediation steps, including engaging legal counsel, initiating an “independent fact-finding process” to identify misconduct, and setting up a separate board subcommittee that does not include any individuals subject to charges or investigation.

“The company takes anti-corruption and the matter at hand very seriously,” PetroNor said.