A federal grand jury in Washington, D.C., sent a subpoena to someone involved in the plane’s development seeking emails, messages and other communications.
Trump announced Wednesday that Boeing 737 Max 8 and Max 9 aircraft in the U.S. were being grounded.
Decision to ground the planes a precautionary move made after a review of all available evidence, Transport Minister told a news conference.
Sunday’s crash was the second fatal flight for a Boeing 737 Max 8 in less than six months.
Airlines have disclosed major issues with the Honeywell emergency locator beacons.