Houdini mice

For months our cats have been staking out our trash compactor. I assumed there must be a mouse somewhere in the vicinity but had never seen a mouse in the house or any signs of one so thought it was probably long gone by now.
Then a couple of weeks ago Nathaniel opened the trash compactor as he was getting ready for school and "they were both just staring at me!" Sure enough there was not one, but 2 mice in the trash. But here was the weird thing--there was no hole in the bag! I couldn't really figure out how they got in there, but they must have somehow squeezed up and over the top of the compactor while it was closed. Gross.
Well Peter's mom Penny was visiting at the time and from that point on I kept seeing trash sitting on the counter top. Turns out Penny wouldn't chance opening the compactor. She said she's experienced more than her fair share of mouse incidents in her life, thank you very much.
hee hee
Yesterday morning John was freaking out--"a mouse is in the trash! I saw it! Come see!"

And here it is--mouse #3. Again no hole in the bag.

We can't really set a trap behind the compactor but we have figure out something. Now I'm thinking there has to be a whole nest somewhere in the wall behind there.
Really, really disgusting.