The engineer of a New Jersey commuter train that barreled into a Hoboken rail station, killing one and injured more than 100, suffered from undiagnosed sleep apnea, it was revealed on Wednesday.

Officials said that Thomas Gallagher, who was operating the commuter train that crashed on Sept. 29, was diagnosed with the condition after the crash, the Associated Press reported.

Investigators are looking into whether this condition was a potential cause of the deadly crash.

Gallagher told investigators that he has no memory of the accident and only remembers waking up on the floor of the cab.