Boston subway "short circuit" blamed after man dragged over 100 feet to his death: "He was literally slaughtered"

A passenger door on a Boston subway car did not function properly when a man got his arm stuck in it and was dragged to his death last month, federal investigators said Monday.

The trains are equipped with safety features to prevent them from moving when the doors are obstructed, the National Transportation Safety Board wrote in the preliminary report.

"NTSB investigators examined and tested the railcar involved after the accident, identifying a fault in a local door control system that enabled the train to move with the door obstructed," the report said.