The union representing the engineer at the helm of the commuter train that derailed Sunday in New York has been ousted from the investigation into the incident for being too chatty. The derailment killed four people and injured more than 60, many of whom remain hospitalized.

The National Transportation Safety Board (NTSB) announced yesterday that the Association of Commuter Rail Employees (ACRE) had been “relieved of party status” because the union violated the rules to which it had agreed.

Under the NTSB's procedures, organizations and agencies are invited to provide technical expertise in support of the Board’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," said the NTSB in a statement.

ACRE General Chairman Anthony Bottalico, conducted a press conference and gave a series of media interviews yesterday, during which he said William Rockefeller, the train’s engineer, “nodded off” at the controls and “zoned out” before the accident. Bottalico said it was a mistake anyone could make.

Those comments put NTSB Board member Earl Weener on the spot during his own press conference yesterday. Weener said it was “premature to be able to say” whether the engineer was fully conscious at all times. He reported the “dead man’s pedal” – which would have stopped the train if Rockefeller had passed out or fainted -- was not engaged.

Bottalico said Rockefeller is deeply affected by the loss of life.

"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.”

Investigators expected to finish interviewing Rockefeller today.