The U.S. Justice Department is scrutinizing the January 5 midair blowout of a Boeing door plug on an Alaska Airlines flight, “in a move that could expose the company to criminal prosecution,” Bloomberg reports.

Four bolts used to secure the door plug were removed and not replaced at Boeing’s factory in Washington, according to a preliminary report by the National Transportation Safety Board.

The DOJ is examining “whether the Jan. 5 incident falls under the government’s 2021 deferred-prosecution agreement with the company over two previous fatal crashes of its 737 MAX jetliner.”

The 737 Max 9 is a larger version of the bestselling 737 Max 8, which was grounded worldwide in 2019 after two fatal crashes killed 346 people within six months. The U.S. returned the aircraft to service in late 2020 after software and training updates.

If prosecutors determine that the Flight 1282 door plug blowout constitutes a breach of that agreement, then Boeing could face criminal liability.

Under the terms of the $2.5 billion settlement, the company adopted a compliance program designed to prevent it from deceiving regulators, including the Federal Aviation Administration. Boeing agreed to comply with the settlement and cooperate with the government for a period of three years, after which the charge would be dismissed.

The Alaska Air accident took place two days before the expiration of the deferred-prosecution agreement.

“If prosecutors determine that Boeing’s handling of the door plug incident over Portland violated the 2021 agreement, they could tear it up and bring criminal charges against the company,” Bloomberg reports.

The Justice Department has six months to determine whether Boeing satisfied the conditions of that deal and needs to seek court approval to dismiss the matter.