By Jonathan Allen
NEW YORK (Reuters) - The driver of a train that derailed in December in New York City, killing four passengers, had an undiagnosed sleep disorder at the time of the accident, his lawyer said on Monday.
William Rockefeller, the engineer at the controls of the Metro-North commuter train that derailed in the Bronx on December 1, suffered from severe sleep apnea, which can cause drowsiness, his lawyer said.
The National Transportation Safety Board, the federal agency investigating the accident, is expected to confirm the diagnosis as a factor in the accident, the New York Times reported on Monday, citing an unnamed person with knowledge of the impending announcement.
"He was fully cooperative with the NTSB and their investigation, including providing his doctors and medical records," Jeffrey Chartier, Rockefeller's lawyer, said in a telephone interview.
The disorder, characterized by shallow or interrupted breathing during sleep, often goes undiagnosed, according to the National Institutes of Health.
Rockefeller's condition appeared to have been aggravated by his being reassigned to an early-morning shift about two weeks before the crash, Chartier said.
An NTSB spokesman said "factual information" regarding the accident may be released later on Monday but declined to provide further details.
Investigators said the seven-car train was traveling nearly three times faster than the speed limit as it approached a curve in the track just outside the Spuyten Duyvil station in the Bronx. Besides the four deaths, more than 70 people were injured.
Rockefeller has said through his representatives that he may have dozed off shortly before the derailment.
(Reporting by Jonathan Allen; Editing by Scott Malone and Bernadette Baum)