Investigators Looking At Maintenance On Track Controls

NORTHEAST DC, (WUSA) -- The exact location of the train is now a critical piece of evidence in the investigation of the deadly Metro train wreck.

The National Transportation Safety Board says earlier this month, Metro performed maintenance work on the train control system embedded in the track between the New Hampshire Avenue overpass and the Fort Totten Station.

Investigators will try and determine if that system might have failed-- giving the train operator very little time to react before impact. "The mushroom... the emergency brake, was depressed," says board member Debbie Hersman. That suggests that train operator Jeanice McMillan did her best to stop the train before it slammed into the back of a train stopped in front of it.

Investigators also found evidence the emergency brakes had deployed. Hersman says there was "bluing" on the brake rotors, suggesting that they were engaged forcefully for an emergency stop.

Published reports also suggest the brakes on Train 112 were two months overdue for replacement. Hersman says investigators have requested maintenance records from Metro, but has yet to review them.