The incident happened at around 4.35pm on Monday 16 August, in Lovers Walk, close to the footpath entrance of Oakmount Road.
A 16-year-old girl was walking along Lovers Walk in the direction of Highfield Lane when she was approached from behind by a man unknown to her.
The man touched her back and told her he just wanted to let her know he was going past. He then wrapped his arm around the girls shoulder and asked to see her breasts before pulling the strap of her dress off her shoulder.
The girl screamed and the man ran off. The girl was not injured.
Officers have been conducting a number of enquiries and are now asking the public if they can help identify the man pictured in the e-fit.
This man is described as:
• Has a prosthetic leg
• Between 40-50-years-old
• Over 6ft tall, skinny with broad shoulders
• Short brown hair – wearing a cap
• Long face with a wide forehead
• Brown eyes
• Prominent brow bone, smile lines and thin lips
• Clean shaven
• Deep voice with local accent
• Wearing an oversized polo shirt, shorts and trainers.
Anyone with information is asked to contact police on 101, quoting 44210326579 or online at https://orlo.uk/bnOmh