A reward of £25,000 remains on offer for information on the deliberate derailment of an Edinburgh to Aberdeen train last year.
The front carriage of the train was derailed in Angus on Sunday November 4.
British Transport Police launched an investigation after an obstruction was found at the scene of the incident involving the 8.04am service from the Capital.
Network Rail and train operators CrossCountry, ScotRail and East Coast said a £25,000 reward is still on offer for anyone who comes forward with information which leads to the arrest and conviction of those responsible.
Detective Chief Inspector Iain Miller said: “Despite the time that has passed since the incident occurred, I am still hopeful that someone will come forward with the piece of information that could help identify those responsible for such an irresponsible act.”
British Transport Police can be contacted on 0800 405 040 or information can be given anonymously to Crimestoppers on 0800 555 111.