The train was traveling 82 miles an hour as it entered a 30 miles per hour curve.
The engineer reportedly has indicated that he may have 'zoned out'.
Investigators are still piecing together what happened, but it turns out there's technology out there to prevent this kind of accident.
Some rail systems have it, but Metro-North does not.
A Metro-North spokesman says the safety feature will be part of the federally mandated 'positive train control system' to be installed by 2015.
But the question remains: why didn't they have it already?
Helping us answer that question and more on the derailment is U.S. Senator from Connecticut, Richard Blumenthal.
Also this week, it was almost 20 years ago that Mayor Rudy Guiliani appointed Bill Bratton as his police commissioner.
Now Bratton is back as the city's top cop, chosen by Bill de Blasio, who campaigned to reform the NYPD, especially the department's controversial stop and frisk tactic.
With us to talk about the appointment is historian and former Guiliani advisor, Fred Siegel, the scholar in residence at St. Francis College and a senior fellow at the Manhattan Institute.
Also, two of the NYPD's fiercest critics react to Bratton's return: New York City Councilman Jumaane Williams, and Jose Lopez of 'Make The Road New York', a community group vocal about reforming stop and frisk.
Watch Up Close with Diana Williams every Sunday morning at 11:00 on Channel 7.