The National Transportation Safety Board says a short circuit in a door control system led to a passenger’s death on the Red Line last month.

Robinson Lalin, 39, of Boston died when his arm became stuck in the closing subway doors and he was dragged more than 100 feet to his death as the train left Broadway station. In its preliminary reporton the fatal accident the NTSB says that MBTA trains are equipped with safety features to prevent them from moving when the passenger doors are obstructed. But investigators found the railcar involved had a faulty door control system that enabled the train to move with the door obstructed.

Lalin’s nephew Kelvin told GBH News:I'm honestly sick to my stomach. I'm still grieving. Just had the service over the weekend. Honestly, we're crushed. The MBTA killed my uncle due to their negligence.” Lalin complained no one from the MBTA had reached out to the family since the accident.

The MBTA did release a statement following the NTSB report extending its “deepest condolences” to the Lalin family. The MBTA said that “immediately following the accident, the door systems throughout out the Red Line fleet were tested for this specific problem, and MBTA personnel found all components performed as designed and did not identify any additional instances of the circuitry problem the incident car experienced.” The MBTA is now supplementing door inspection protocols to prevent a repeat of this failure.

The T did confirm the car involved was one of the oldest in the subway fleet, first put into service in1969. The MBTA is in the process of replacing all its Red Line and Orange Line cars.

Meanwhile investigations by the NTSB, Transit Police and the MBTA Safety Department into the fatal accident continue. The T says if further steps are warranted to enhance safety, then they will take immediate and appropriate action.