THREE people could be key to catching a sex attacker.

Detectives believe a woman and two men pictured on CCTV may have seen the attacker shortly before he targeted a 19-year-old woman in the West Lane area of Chester-le-Streeet, at about 4.30am on Saturday, August 4.

The victim was walking through Pentland Court, towards the town centre, to catch a taxi home when the man pulled out a knife and subjected her to a serious sexual assault.

In the four weeks since the attack, Durham police have issued an E-fit of the man, prompting a number of calls from the public.

Officers have also pored over hours of CCTV footage from the area, releasing images of potential witnesses yesterday.

They want to speak to a woman, pictured walking past the Argos store, in Front Street, at 4.29am, wearing a light-coloured coat or jacket, and the two men, possibly in their twenties, seen getting off the Newcastle to Durham all-night 21 bus service at 3.49am.

Detective Inspector Kevin Langan said: "The response to the posters and other publicity has been very encouraging, with several names put forward.

"But we would like to speak to the people in these photos as a matter of urgency, and anyone else who was in Chester-le-Street, especially in the West Lane area, between 4am and 5am that morning.

"I must stress we are treating the woman outside Argos and the two men on the bus solely as potential witnesses. It is possible they saw the man who carried out the assault and, for that reason, I would value their assistance."

The attacker is described as about 40, 6ft, stocky, with very short or shaved hair, a round face, stubble on his chin and wearing a long-sleeved dress shirt.

Extra police patrols will be in Chester-le-Street's bars and clubs on Friday night, with officers available to speak to anyone who can help the investigation.

Anyone with information is asked to contact Det Insp Langan, through Chester-le-Street CID, on 0845-60-60-365 or call Crimestoppers on 0800-555-111.

A man who was arrested in connection with the offence was released without charge.