A council's "dog fouling squad" has described how undercover surveillance caught not a dog - but a man.
The undercover squad spotted the difference
The CCTV operation was set up after a member of the public made a complaint to Kirklees Council in West Yorkshire about a mess often left at Cleckheaton.
Councillor Martyn Bolt said an investigation found the deposit was the work of a human.
He said: "With the aid of CCTV the culprit motorist was caught on camera with his trousers down - literally."
He added: "It subsequently became apparent that this was not an isolated occasion, but appeared to be a regular stopping-off point.
"It would appear that the man concerned regularly travelled between Birkenshaw and Brighouse and, instead of finding a public toilet, pulled up at the side of the road to do his 'business' there and then.
"It seems he regularly got taken short at the same place."
He said the man had been traced and the matter was now in the hands of the police.
He added: "There really is no excuse for this sort of unacceptable behaviour which, in this case, may well have ended up in the 'give a dog a bad name' category had the complainant and our officers not spotted the difference."