The National Transportation Safety Board (NTSB) has released a preliminary report in connection with the ongoing investigation of a Boston subway passenger’s death, stating Monday that a “fault in a local door control system” was to blame.

Robinson Lalin, 39, was dragged to his death last month after his right arm got trapped in the railcar’s door while attempting to exit. Per a report from the Associated Press, the system is designed with various safety features that are meant to prevent trains from moving when a door obstruction occurs. In their report released Monday, the NTSB said its investigators “examined and tested” the railcar involved with Lalin’s death and found the aforementioned door control system issue.

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

In a separate statement, per a regional NBC outlet, the MBTA—i.e. the Massachusetts Bay Transportation Authority—addressed the release of the NTSB report and said its initial findings were in line with its own.

“The NTSB has confirmed the MBTA’s initial assessment of a short circuit in the car’s wiring that allowed the train to begin moving while Mr. Lalin was attempting to exit through the closing doors,” an MBTA rep said.

Lalin was dragged an estimated 105 feet “and onto the surface below, near the tracks” after his arm became stuck in the door on April 10 at the Broadway Station in Boston. In initial reports last month, it was noted that the train operator had been removed from duty as agencies awaited investigation outcomes.