Police are searching for a man who has been defecating on trains across the country, causing tens of thousands of pounds-worth of damage.
The offender has struck on at least 30 trains since August, mainly in the Southeast, smearing excrement inside the carriages.
He waits until he is alone in the carriage before committing the offence.
His "exceptionally anti-social" actions have caused a total of £60,000 worth of damage, and even resulted in carriages being taken out of service.
British Transport Police warned today that his unpleasant habit was creating a risk to public health. The force has released CCTV images of a man officers want to speak to in connection with the investigation.
Detective Constable Donna Fox said: "The man has struck at least 30 trains since August, causing approximately £60,000 in damage and cleaning costs, causing serious inconvenience to the travelling public.
"This is obviously a serious public health issue as well as being exceptionally anti-social. We need to locate this man as soon as possible."
She continued: "On at least one occasion CCTV footage shows the man being disturbed by a passenger walking through a train. We are appealing for this passenger to contact us.
Anyone with information should call the BTP Witness Appeal line on 020 7391 527...SUPL: