Raccoon Bowling Night at Abbie's!

Well, there were no noises in the closet last night, but I swear there was bowling on the roof! I could hear scurrying across the roof and a couple of thuds every few minutes. It literally sounded as if the it was bowling night for the wildlife!
After checking the traps this morning, I found no signs of extra critters in the house.
I ran an errand and was gone no more than thirty minutes. When I returned, Abbie was waiting to go outside at the back door. I let her out and she went straight into the shrubs that line the back of the house and she kept looking at the roof. I said 'What is it, Abbie?' and she intently looked up at the roof. She was not taking her eyes off the roof and she was in hunt mode, relentlessly sniffing out the shrubbery and the earth around it. She definitely knew there was something on the roof and it had been down on the ground earlier. She must have been watching whatever it was out the back door while waiting for me to come back in. She did not give up until I said 'Okay Abbie....you chased it off' and we returned into the house.
My guess is that this is a opossum or a raccoon and it has access to the house via the vents on the roof and the wall entries. I am very surprised this is the first we are hearing from this critter, but I hope it takes up space somewhere else in a hurry because Abbie's mommy is not going to want to come home!!!!