Garden Advice - My mulch is a litter box.

With spring right around the corner I am looking forward to my flowers, believe it or not some have already started to sprout.  Well all of this and the fact that the fat orange cat is laying in my mulch now, reminds me of last year.

Oh it was beautiful - rich cedar mulch, beautiful flowers, perfectly trimmed bushes and a cat crapping in my mulch,  WHAT?!  Yes, this stupid fat ugly annoying cat (for many reasons and I am a cat lover but I hate this cat) craps in my mulch.  This was not what I had in mind, well this summer I am up for a fight.  I've considered a large squirt gun, won't hurt but I bet after a few shots he won't come back.  His owner is a real ****, he calls the cops on other people's pets but his can do whatever it wants.

 So my question is any advice on getting this cat to stop using my garden as a personal litter box?  I don't want to hurt it but I do want it to stop and quickly as possible.  I've heard there are chemicals and stuff but I'm not sure if they work so curious if any of you out there know any good ones or tried and true solutions.