Detectives investigating the rape of a 15-year-old girl in a school field in Dorset say they have a DNA profile of the suspect.
The teenager was attacked at St Osmund's Middle School in Dorchester at about 21:20 GMT on Thursday 5 December.
She was forced to the ground by a man carrying a pocket knife.
Dorset Police said the DNA information would allow detectives to "quickly and definitively" eliminate anyone not involved.
The attacker is described as white and aged between his mid 20s and mid 50s. He was wearing a grey puffa-style jacket with the hood up, light coloured trousers and leather gloves.
Detectives previously issued CCTV images of the suspect and urged residents in south-east Dorchester to check their CCTV and dashcams for similar footage recorded that evening between 18:00 and 22:30 GMT - the same night as the Dorchester Christmas Cracker event.
Det Insp Wayne Seymour said: "We have obtained home CCTV footage believed to show the suspect in the area at the time of the offence.
"I am hoping it might help any witnesses who may have seen this man in the vicinity."