Moschops, I feel your pain. I recently had a rather large deposit left a little way up my driveway. I have suspicions of which dog and owner are responsible, but can't prove it.
There is another dog and owner who regularly walk on my street, and their dog loves dropping a load up the road from me. Quite irritating when the neighbour confronted me while I was walking my dogs and accused me, outright, no doubt.

As a dog owner it is REALLY irritating to see other owners allowing their dogs to do this, and even more annoying being blamed for someone elses behaviour.

With regards to stopping it, you can sadly sometimes find that a strong smelling cleaner will actually encourage a dog mess. Hope you get to the bottom of it though. These people need fining. Especially the phantom crapper of Church Rise!