Thanks for your suggestions. Usually I don't give him a chance to get out my window -- I accidentally left my door open though. I will try nailing it down like you said; that should do the trick! I don't let him in my room because he pees on the bed, but there are times when my head just isn't there and my door is left open.

Normally I would have just left my window open after he escaped and stayed in my house to wait for his return, only my neighbors' cats were killed by my other neighbor, and that cat murderer that was slaughtering cats in my area still hasn't been caught. I just don't want to take the chance. I hope Caleb won't get out anymore!

Thanks again.