Do you recognise this man?
Officers would like to speak to him in connection with an outraging public decency incident on a train to Aylesbury on 11 June.
At approximately 10.15pm, a man was seen to inappropriately touch himself while looking in the reflection of a woman in a window who was sat in the same carriage.
The incident happened shortly before arriving at Aylesbury station, where the man left the train.
Officers would like to speak to the man in this CCTV image as they believe he may have information which could help the investigation.
If he looks familiar or you have any information which could help the investigation, please call 0800 40 50 40 or text 61016, quoting 316 of 4 September. Alternatively, you can ring Crimestoppers anonymously on 0800 555 111.