Police are investigating an "horrific" sexual assault on a woman walking her dog near school fields.
The 25-year-old woman was attacked on Tuesday, 31 July, near St Bernadette Primary School in Pentwyn, Cardiff.
South Wales Police said it was "an isolated incident" and they were appealing for witnesses.
They described the attacker as "mixed race," aged 20 to 30, of slim build, and with unkempt dark brown or black spiky hair.
Officers have been carrying out CCTV checks, house-to-house inquiries and forensic examinations.
Detective Sergeant Rob Cronick said: "This is an isolated incident and is irregular for Cardiff and this area.
"It is however a horrific incident and we are appealing for witnesses to come forward."
She was approached by a man who grabbed and threatened her before sexually assaulting her between 2000 GMT and 2100 GMT.
Officers described the man as being between 1.67m - 1.76m (5ft 5in - 5ft 8in) with a mole on the right side of his face on the lower cheek or chin.
Police said the lane where the assault took place, between Pentwyn Drive and Wharfedale Road, was popular with dog walkers.
They said it was a short cut for people living on the estate or using the nearby Village Inn pub.
Anyone with information can contact Rumney police station on 029 2077 4233 or Crimestoppers anonymously on 0800 555111.