NEW YORK — AP is reporting that National Safety Transportation Board (NTSB) investigators looking into the derailment of a Metro-North train on Sunday found no problems with the brake system or track signals along its route, while the engineer was being questioned again.

The Metro-North Railroad commuter train was traveling at 82 mph as it approached a 30 mph zone and jumped the tracks along a sharp curve, killing four passengers. For the full AP report, click here.

Meanwhile, two law enforcement officials told NBC 4 New York that the train’s engineer said he zoned out just before the crash and was not able to recall specifics about the moments before the accident.

The NTSB said at a Tuesday briefing that authorities could not yet describe the engineer's condition just before the crash. Investigators are still probing whether human or mechanical error was responsible for the train speeding. For the full story, click here.

Additionally, the NTSB removed the Association of Commuter Rail Employees, or ACRE, as a participant in its investigation into the derailment.

Under the NTSB's procedures, organizations and agencies are invited to provide technical expertise in support of the NTSB's investigation. The organizations designated as parties sign an agreement to abide by NTSB rules for the duration of the investigation. Maintaining confidentiality of investigative information is one of the rules that parties agree to, further, they agree that their organizations will neither reveal nor comment on investigative information.

On Tuesday, Anthony Bottalico, general chairman of ACRE, conducted a press conference and a series of media interviews during which he discussed and interpreted information related to the ongoing investigation. As a result of this violation of the party agreement, the organization was advised it was removed from the investigation.

"While we value the technical expertise that groups like ACRE can provide during the course of an investigation, it is counterproductive when an organization breaches the party agreement and publically interprets or comments on investigation information," said NTSB Chairman Deborah A.P. Hersman. "Our rules exist to avoid the prospect of any party to an NTSB investigation offering its slant on the circumstances of the accident."