Thames Valley Police is appealing for witnesses following an incident of indecent exposure in Milton Keynes.
At approximately 7pm on Wednesday 24 January, the victim was in her living room at a property in Darnel Close, Beanhill.
The living room backs on to a rear garden, separated by glass patio doors.
The victim heard a knock on the door and as she approached the patio doors, saw a man indecently exposing himself with no trousers on.
The victim retreated into her house and did not see the offender again.
The offender is described as a white man, aged in his early twenties and around 5ft 8ins tall.
He was wearing a tight black face mark, potentially with a black hood up.
He appeared to be wearing no trousers and there was a flash of colour around the shoulders, which may have been part of an outer layer of clothing.
Investigating officer PC Ashleigh Vendy, of the Milton Keynes South Neighbourhood Team, said: “This was a frightening incident for the victim, who saw the offender in her back garden indecently exposing himself.
“The offender left the scene, and I am appealing to anybody who was in the area and witnessed any suspicious activity, or believes that they saw the offender, to please get in touch with Thames Valley Police.
“I would also urge people in the local area to please check their CCTV, doorbell cameras or dash-cams and contact us if it has captured the anything that may assist this investigation.
You can get in touch by making a report online or by calling 101, quoting reference 43240036810.
“Alternatively, you can call the independent charity Crimestoppers anonymously on 0800 555 111.”
