By Keith Laing - 12/03/13 01:41 PM EST
The operator of a Metro-North train that derailed over the weekend and killed four passengers was "not 100 percent awake," according to reports.
The New York Times and New York City's ABC News affiliate reported on Tuesday that the engineer who was operating the Metro-North train when it derailed in the Bronx on Sunday morning told the federal investigators that he was “almost hypnotized” in a trance at the time of the accident.
“That place where you’re not asleep and you’re not 100 percent awake,” the paper quoted an anonymous source, who it said was familiar with the accident investigation, as describing Metro-North engineer William Rockefeller.
The train derailed on Sunday morning after making nine successful stops en route to New York City from Poughkeepsie, N.Y.
The NTSB has said the train was traveling at 82 miles per hour in an area of track that had a 30-mile-per-hour speed limit and a very sharp curve.
The Times reported that, based upon text messaging and call records, Rockefeller did not appear to have been distracted by his cellphone or under the influence of drugs or alcohol.
The lead investigator on the accident said in an interview with CNN that the agency was considering operator error as a potential cause of the fatal train crash.
NTSB board member Earl Weener said the doomed train's brakes appeared to be working when it made its other stops before the derailment.
"We don't know whether it was human error or mechanical failure," Weener said during an appearance on CNN's "Situation Room."
"That, of course, is the reason why we'll be continuing this investigation with a great deal of intensity," Weener continued. "But that's what we want to find out."
The NTSB is scheduled to hold a briefing on the Metro-North accident investigation Tuesday afternoon.