A man has been arrested by police investigating the report of a serious sex assault in a park in Powys.
Dyfed-Powys Police said its search teams were in Rock Park in Llandrindod Wells, following Saturday's incident.
Police want to trace a man in a green raincoat, aged 30-40, who may have seen the victim, a young woman, between 1200-1300 BST.
A man is in custody and is being interviewed.
The force said officers were making house-to-house inquiries.
A spokesman said the potential witness they want to speak to had dark hair and a stubbly chin.
Police believe he may have seen or brushed passed the victim.
"We would ask this man to come forward as he may have valuable information that would assist the enquiry," said the force spokesman.
Anyone with information is asked to contact police on the non emergency number of 101 or by ringing Crimestoppers on 0800 555111.