A £25,000 reward has been offered to anyone who can help police find the people responsible for derailing a train.
Major disruption was caused on the east coast railway line after the front wheels of a CrossCountry Trains vehicle came off the tracks at Inverkeilor between Arbroath and Montrose in Angus on November 4.
Services between Aberdeen and Edinburgh were suspended as a result of the incident. The train came off the tracks but remained upright and none of the 36 passengers or two staff were seriously injured.
British Transport Police said they believe an object that derailed the train was put on the track deliberately but would not say what it was.
In response to the incident, a reward has been offered by the rail industry for information that leads to the arrest and conviction of the people responsible.
Network Rail, the operator of the railway infrastructure, has joined together with train operators CrossCountry Trains, ScotRail and East Coast to fund the reward.
Detective Inspector Kevin McCormack, of British Transport Police (BTP), said: "It is hoped that by offering such a substantial reward someone will come forward with information that can help identify those believed to be responsible for such an irresponsible act."
David Simpson, Network Rail route managing director for Scotland, said: "This incident could have caused a very serious accident on the railway and put lives at risk.
"We are determined to do everything we can to support the police in their investigation and would encourage anyone with information about this stupid and reckless crime to get in touch immediately."
The BTP continue to investigate the incident with assistance from Tayside Police.