Police officers are appealing for witnesses after a ticket examiner was threatened and assaulted on train travelling between Aberdeen and Laurencekirk.
The incident took place on the 10.27pm Aberdeen to Dundee service at around 10.40pm on Saturday.
British Transport Police said the 35-year-old male member of staff was grabbed around the throat by a man in his mid 50s “for no apparent reason” as the train approached Portlethen station.
The suspect, who is described as bald and of heavy build, was wearing a black jacket, black trousers, a blue shirt and a black scarf.
He got off at Laurencekirk just before 11pm.
Officers have reviewed CCTV footage and the man responsible is seen being dropped off by the driver of a silver estate car around 1.30pm the same day.
Constable Nicky Ritchie is appealing for anyone who was on the train or at the station and has information which can help the inquiry to contact British Transport Police on 0800 40 50 40 or by texting 61016.