CSI Cat Poo Method?

Grate crayons of two colors (probably non washable as washable may digest). Feed cats seperately and wait. I did this and it worked perfectly. The cat that I was so sure was the perp ended up being innocent.

Try using two litter boxes. I also have two cats and sometimes the same thing happens. They like to claim their own space so the two boxes helped. Also are they big cats? Both of my cats are very large cats and you need to buy the extra large size litter pans so they can fit properly in it. Also if the litter box is not clean all the time they will inch their way to the corner when using it to avoid stepping into anything unpleasant.

Good Luck

if you're going to that much trouble... why not set up a video camera instead? then when you have the evidence... rub the guilty cats nose on the t.v. screen!

Why not just add red food coloring to one cats food. It doesn't light up, but it would be easy to see!!!!!!!

use a dye but don't know what call a pet store how do i start a pon site?

If you can get ahold of it, fluorescein would do nicely.

corn or seeds of any type.