The U.S. Justice Department has joined a group of international agencies investigating how thousands of bogus engine parts backed by forged documents ended up in planes around the world, according to people familiar with the matter, as fallout grows over a scandal that has spread across the commercial aviation industry.

The DOJ has sought information from at least one airline that removed unapproved parts linked to AOG Technics, according to one of the people, who asked not to be identified because the information isn’t public.

The Justice Department’s involvement marks the first indication of scrutiny by law enforcement into the issue, which was reported by Bloomberg News in August. The probe is in its early stages and may not result in charges. At least one non-U.S. authority has shared information with other enforcement agencies, according to another person, indicating a coordinated effort to pursue the case across national boundaries.