The US Justice Department has opened a criminal investigation into the midair blowout of a Boeing 737 Max fuselage panel on an Alaska Airlines flight in January.

“In an event like this, it’s normal for the DOJ to be conducting an investigation,” Alaska Airlines said Saturday in a statement. “We are fully cooperating and do not believe we are a target of the investigation.”

The Wall Street Journal reported that investigators have contacted some passengers and crew members from the flight, which made an emergency landing in Portland, Oregon, after a door plug ripped off from the plane.

A Boeing Co. spokesperson declined to comment. The Justice Department didn’t immediately respond to a request for comment.

Separately, Boeing confirmed it can’t locate any records of the work performed on the door panel that failed and suggested company procedures weren’t followed, according to a letter sent to a US senator who leads the committee overseeing aviation issues.

Bloomberg reported last month that the Justice Department was scrutinizing the Alaska incident, examining whether it falls under the government’s 2021 deferred-prosecution agreement with the aircraft maker over two previous fatal crashes of its 737 Max jetliner. 

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 on Jan. 5, two days before the expiration of the deferred-prosecution agreement.

Boeing’s acknowledgment that it lacks records for what appears to have been a faulty repair shortly before the jet was delivered last year is highly unusual in an industry that places enormous emphasis on documentation.

The Boeing team working with the National Transportation Safety Board “has shared multiple times with the NTSB that we have looked extensively and have not found any such documentation,” Ziad Ojakli, executive vice president of government operations, wrote in the letter.

It was sent to Senator Maria Cantwell, the Washington Democrat who chairs the Commerce Committee. The letter was earlier reported by the Seattle Times.

A panel covering an unused door was installed without four bolts that would have prevented it from coming loose, the NTSB said in a preliminary report last month.  

Ojakli defended Boeing’s work with NTSB, saying it had provided the investigation team with all the requested information. NTSB Chair Jennifer Homendy on Wednesday accused Boeing of failing to cooperate in the probe. NTSB spokesman Eric Weiss said Homendy stands by her testimony before the Commerce Committee.