Police are trying to identify a man who is suspected of carrying out a sex attack on a train between Brighton and Southwick.
The attack, on a teenage girl, is alleged to have happened 10 days before Christmas, the British Transport Police (BTP) said.
The BTP said: “Do you recognise this man?
“Detectives investigating a sexual assault on board a train between Brighton and Southwick in December have today released this image in connection.
“At around 5.30pm on Sunday 15 December, a teenage girl was sat on the train when a man sat opposite her where he tried to talk to her but she did not respond.
“As the teenage girl stood up to get off the train the man has sexually assaulted her.
“Officers would like to speak to the man in the images as they believe he may have information which could help with their investigation.
“Anyone who recognises him is asked to contact British Transport Police by texting 61016 or by calling 0800 405040, quoting reference 527 of 15 December.
“Alternatively, you can contact Crimestoppers anonymously on 0800 555111.”
The usual suspects