'Vital' witness in sex attack hunt

A woman who is believed to have walked down an alleyway while a teenage girl was being sexually assaulted could have some vital evidence for police.

Detectives in Hertfordshire appealed on Wednesday for the woman, who may not have realised what was happening, to contact them.

A 16-year-old girl was attacked and sexually assaulted in an alleyway off Bridge Road, Stevenage, at about 0200 BST on Saturday.

Detective Inspector Dave Laming said the passer-by may hold some vital clues which could lead to the identity of the attacker.

Teenage attacker

"This was a very serious incident and we are very keen to hear from any witnesses or anyone who thinks they saw or heard anything suspicious in the area between Stevenage old town and Bridge Road," he said.

"In particular, we believe a woman may have walked past the scene as the incident was occurring in Bridge Road.

"This woman may not have realised what was taking place at this stage but we really need to hear from that woman."

The attacker was described as a white man, about 18-years-old, 5 ft 10 in tall, with a slim build and was wearing a hooded top.