A woman was walking her dog near to a lake in a Northampton park before a man exposed himself before vanishing.
The incident happened between 9.10am and 9.40am on Sunday, October 1, Northamptonshire Police today revealed.
The woman was walking her dog near to the lake in Eastfield Park off Kettering Road.
She noticed a man standing near the treeline, which starts at Skiddaw Walk, before he exposed himself and disappeared into the trees.
A Northamptonshire Police spokeswoman said: "The offender is described as a white man, 25 to 30 years old, with tanned skin and wearing a blue hooded top and jeans."
Anyone with information can contact Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.