The man who was killed on the MBTA's Red Line early Sunday was exiting the train when his arm got caught in the door, according to a National Transportation Safety Board spokesperson.
The new detail announced Friday is a peek into what happened the night 39-year-old Robinson Lalin was killed. Not much else is known about the incident last weekend.
Jim Borghesani, a spokesperson for the Suffolk district attorney's office, said earlier this week Lalin's arm got trapped in the door and he was pulled along by the moving train.
The train involved was more than 50 years old and has been taken out of service. T officials say the train's operator has been removed from duty during the investigation.
A typical investigation can take one to two years.
According to the NTSB spokesperson, a preliminary report could come in a couple of weeks, but it will not state a cause for the incident.
With reporting by WBUR's Darryl C. Murphy