Police are appealing for information after a man outraged public decency on Greenway, Cleckheaton.
The incident happened on Sunday August 17 at 5.55pm close to the bridge that runs over the Greenway on Whitcliffe Road.
A man officers want to speak to in connection with the incident is described as white, wearing a bright orange baseball cap and a beige jacket.
Officers are also keen to trace a man who walked past the victim and towards a bush in which the suspect was hiding. Police want to speak to this man as a witness.
PC Mark Jones of the Heckmondwike Neighbourhood Policing Team, said: “I would appeal for any witnesses - especially this man - to come forward and get in contact. Contact police on 101.”