British Transport Police are seeking assistance in relation to a public indecency offence on a train between Glasgow Central and Clarkston stations.
Officers have released CCTV images of a male they believe may be able to assist with their enquiries in relation to the offence.
The incident happened shortly after 9.45pm on Saturday, February 9.
Officers believe the man in the image may have information that could help their ongoing investigation.
Anyone who recognises the man, or who has more information about the incident, is asked to contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference number 727 of 09/02/2019.