An assault of a sexual nature was made towards a woman in a Grantham park on Friday afternoon by a man brandishing a weapon.
A 26-year-old man, who was residing at North Sea Camp, an open prison in Boston, was arrested a short time later and has been remanded in custody.
The woman was allegedly approached by a man holding a blade and threatened. She was not physically injured, said a police spokesman.
A police cordon was in place around a wooded area of Queen Elizabeth Park for several hours following the incident.
The man arrested is charged with possession of a bladed article and common assault with the intention of committing a relevant sexual offence. A second charge is possession in public of article which had a blade or was sharply pointed.
He was remanded into custody to appear before Lincoln Crown Court on July 15.