HE could be the vital witness who can help solve a horrifying sex attack on a man in Southampton.

It was five weeks ago today, in the early hours of the morning, when the victim was attacked, robbed and then raped as he walked home after an evening out.

Detectives have today released this image of a man they are trying to trace, who they believe could lead them to finding the attacker. They are keen to stress he is very much a witness who was seen on CCTV walking just a short distance behind the man when he was assaulted.

The victim was walking along Portsmouth Road on Saturday April 21 and was close to the Vospers sports ground and the entrance to Upham Motor Company when he was confronted by a man on a bike.

He was punched in the face and had his mobile phone taken, before being led back in the direction he had come from, onto a dark footpath opposite Ashley Crescent, and seriously sexually assaulted.

Police think the witness may have left a house in the Butts Road area of Sholing, possibly having attended a party.

Detective Inspector Dave Morgan said: “Due to the timing of this person being seen on CCTV and the fact that he was walking in the same direction as where the assault took place I believe that he would have seen our victim walking in front of him.

“It is also likely that he would have seen the initial confrontation and the offender, or heard something that could be crucial to our investigation.

“It is paramount that he contacts us. I would like to stress that he is not being viewed as a suspect but purely as a potentially crucial witness.”

The road is a popular route home for people leaving the city after a night out and police know there were many people both walking and in cars that night. They are appealing for anyone who saw anything suspicious between 2.30am and 4am to contact them on 101.