British Transport Police (BTP) has released a CCTV image of a man they believe can help with enquires into an assault last month.
BTP believe the man may be able to assist with investigations into the assault on a 53-year-old woman on Saturday, October 3.
The incident occurred on the 9.48pm Edinburgh Waverley to Perth service, just before the train reached Dalmeny.
The man in the photograph is described as being aged in his mid-30s, about 5ft 8in in height with brown hair and a beard.
He was possibly wearing dark-rimmed glasses and a brown jacket.
He alighted from the train in the company of another man at Dalmeny station.
Constable David Ferguson, the BTP officer in charge of the enquiry, said: “I am appealing to anyone who recognises the man shown in the photograph to contact me as a matter of urgency.”
Anyone with information should contact British Transport Police on 0800 40 50 40 or by texting 61016.
Information can also be given anonymously to the independent charity Crimestoppers on 0800 555 111.