A PRELIMINARY REPORT released by the National Transportation Safety Board indicates a “fault in a local door control system” was likely the cause of an April 10 accident on the MBTA’s Red Line that resulted in the death of 39-year-old Robinson Lalin of Boston.

The preliminary report, released Monday morning, said Lalin was fatally injured as he attempted to exit the train at Broadway Station as the train doors were closing. Details were not provided, but it appears that somehow Lalin made it through the door and then got his arm snagged as the door clamped shut.  “The train departed the station, dragging the passenger along the platform about 105 feet and onto the surface below, near the tracks,” the report said. 

MBTA subway vehicles are equipped with safety features that prevent the cars from moving when the doors are obstructed. The report said the National Transportation Safety Board tested the vehicle after the incident and discovered the fault in the door control system.

“The MBTA immediately initiated a fleet inspection looking for the identified fault in other railcars to prevent reoccurrence. The MBTA reported that no other similar faults were found during the inspection,” the report said.

The safety board said the investigation is continuing and will focus on the MBTA’s passenger train equipment and operating procedures.  The report said the parties to the investigation are the MBTA, the Massachusetts Department of Public Utilities, the Federal Transit Administration, and the Boston Carmen’s Union.