A woman was subjected to a serious sexual assault as she walked home after a night out in Richmond.
The 20-year-old was attacked by a man in his 40s as she took a short cut between Pottergate and Olav Road in the early hours of Monday.
Officers are checking CCTV footage and carrying out door-to-door inquiries.
The woman's attacker is described as 5ft 6in to 5ft 7ins tall, with a tan and closely-cropped brown hair. He wore a cream-coloured top and blue jeans.
Acting Det Insp Matt Walker said: "It's vital that we bring the attacker to justice as quickly as possible and I urge witnesses or people with information that would aid the investigation to get in touch immediately."