Detectives investigating a sexual assault on board a train from Billingham to Hartlepool have released this image in connection.
At around 9.45pm on Friday 3 April, a woman on the train bumped into a man who had boarded at Middlesborough.
The man initially sat across from the woman but moved to sit next to her before he sexually assaulted her.
He then left the train at Hartlepool.
Detectives believe the man in the image may have information which could help their investigation.
Anyone who recognises him is asked to contact British Transport Police by texting 61016 or by calling 0800 40 50 40, quoting reference 861 of 3 April.
Information can also be given anonymously to Crimestoppers on 0800 555 111.
