SEATTLE, Wash. — A public radio station’s investigation points to sabotage as the cause of the train derailment and explosion in Custer last December.

KUOW says it’s received a transcript of interviews conducted during the investigation.

A safety team member with the union that represents the train’s crew told BNSF investigators that, judging by how trains and their equipment work, “that this incident was caused without a doubt by sabotage.”

A retired rail investigator backed that up, saying that whoever did it had knowledge of railroad equipment and air-brake systems.

BNSF had accused the rail crew of failing to respond after their braking system was compromised.

The oil train derailed north of Bellingham while slowly pulling a mile-long load of petroleum tankers to the Phillips 66 refinery at Cherry Point.

No one was injured in the explosion and fire.

The FBI, the Federal Railroad Administration, and the National Transportation Safety Board continue their investigation and an official cause of the derailment won’t be announced until its complete.