Beware!!!!

So I get up each morning, take Arthur out and check on our Gardening School project.  Well this morning I discovered something had been messing around, digging and knocking down my young, tender plants. 
I immediately knew it had to be the rabbits that frequent our yard in the Spring. We have had bunnies in and out of our yard for years now.  Last Spring Arthur killed several(I think 3 or 4)babies so I was not too excited about them being back.  Although me and the boys did enjoy watching the momma come early in the morning to check out the yard.  She even would hang around(which I learned is not normal)going from the backyard to the front.  I can remember times sitting at my desk(right next to the patio doors)and seeing something out of the corner of my eye.  It was the momma bunny hopping through the yard.
OK I am a lover of ALL creatures, but I have now discovered it was NOT a sweet bunny trying to find a home for her young.  It was a dang CAT!  And I am going to kill it!  I went back out this morning to see if the hole had anything in.  BTW this is how we discovered baby rabbits last Spring.
Oh the hole had something in it alright!!! Cat POOP!  I was and am so mad! 
So now I am on a mission to kill a cat or figure out how to keep this bold animal from using our garden as his litter box!  Beware cat!
Got any ideas?  Please send them my way.  Otherwise I'll post a picture of a dead cat hanging on the fence.
(Just kidding.......I couldn't do it, but Brant would!)