The dead were identified as Donna L. Smith, 54, of Newburgh; James G. Lovell, 58, of Cold Spring; James M. Ferrari, 59, of Montrose; and Kisook Ahn, 35, of Queens.
Some of the injured remained hospitalized Monday, including seven in intensive care at one hospital and two patients in critical condition at another.
The train was configured with its locomotive in the back instead of the front. Weener said that is common, and a train's brakes work the same way no matter where the locomotive is located. Ditmeyer said the locomotive's location has virtually no effect on train safety.
Still, some people feel the configuration provides less protection for passengers because if the train hits something, there's no locomotive in front to absorb the blow, said Bill Henderson, executive director of the Permanent Citizens Advisory Committee to the MTA, a riders' advocacy group.
The derailment came amid a troubled year for Metro-North, and marked the first time in the railroad's 31-year history that a passenger was killed in an accident.
In May, a train derailed in Bridgeport, Conn., and was struck by a train coming in the opposite direction, injuring 73 passengers, two engineers and a conductor. In July, a freight train full of garbage derailed near the site of Sunday's wreck.
Repair work on the latest derailment damage continued on Metro-North's Hudson Line, which normally carries 26,000 weekday riders.