People who were aboard a Boeing 737 Max 9 jet whose door plug was explosively expelled after departing an airport in Portland, Ore., in January are being contacted by the FBI about a criminal investigation.

“I’m contacting you because we have identified you as a possible victim of a crime,” the letter from a victim specialist with the FBI’s Seattle Division begins.

The message, a copy of which was shared with NPR by Mark Lindquist, an attorney representing passengers, lists an investigative case number and tells the passengers they should contact the FBI through an email address set up specifically for people who were on the flight.

Boeing had been accused of engaging in a criminal conspiracy to defraud the Federal Aviation Administration, as the regulator evaluated its 737 MAX airplane.

“Federal prosecutors say key Boeing employees ‘deceived the FAA,’ misleading the safety regulators about a new flight control system on the 737 Max called MCAS,” as NPR reported in January of 2021.

The deferred prosecution agreement had been set to expire three years after it was filed on Jan. 7, 2021. But the agreement also allows the DOJ’s Fraud Section to extend its heightened scrutiny for up to an additional year if Boeing is found to have failed to fulfill its obligations — including the airplane company’s promise to strengthen its compliance and reporting programs.