The captain of the Germanwings plane that crashed earlier this week, apparently at the hands of a co-pilot, was identified Saturday as Patrick Sonderheimer.
Sources confirmed the captain's name to NBC News, but little else was immediately known about him.
Sonderheimer's 27-year-old co-pilot locked him out of Germanwings Flight 9525's cabin and steered the plane into the French Alps on Tuesday, killing all 150 on board, investigators said.
The co-pilot, Andreas Lubitz, left no suicide note, but German prosecutors said they found torn-up doctor's notes excusing him from work while searching his home. Germanwings has said it did not receive a sick note for the day of the crash.
Investigators did not elaborate on the illness, or say whether it was mental or physical. Sources told The New York Times and The Wall Street Journal on Saturday that Lubitz had been examined for vision problems that could have affected his ability to do his job, but that was not verified by NBC News.
The cockpit voice recorder taped Lubitz and the captain talking naturally and having a "very normal conversation," Marseille prosecutor Brice Robin told a news conference earlier this week. Just before 10:30 a.m., Robin said, the captain left the flight deck — likely to take a bathroom break — and handed controls to Lubitz.
A couple of minutes later, Lubitz put the plane into an unapproved descent, Robin said. The captain was heard trying to get back in through the double-locked door on the flight deck, calling out to his co-pilot and knocking, but Lubitz never responded, Robin said.
Lubitz said nothing in the final eight minutes leading up to the crash, but his breathing could be heard. An altitude warning sounded as the plane neared the mountaintops; the next sound was more forceful banging on the flight deck door, Robin said. The last sounds on the cockpit recorder before impact were passengers' screams.
This article originally appeared on NBCNews.com.