Police have released images of a man they wish to speak to in connection with an assault and robbery in Tranent in East Lothian.
It happened on the number 26 Lothian bus as it travelled through the High Street area at about 07:00 on Saturday 2 June.
The victim suffered minor injuries.
Officers believe the man pictured may be able to assist the investigation. They have appealed for anyone with information to contact them.
The man is described as about 5ft 8ins tall and of slim build, with short brown hair and a birth mark on his right cheek.
He was wearing a grey or green coloured tracksuit.
Det Con Bruce Dodds, of Police Scotland, said: "We're eager to trace the man pictured as soon as possible and ask anyone who can help us identify him to get in touch at their earliest opportunity.
"Similarly if the man himself sees this appeal then I urge him to contact us."