Lost Pet: Kookies

Circumstances

We were on vacation, using a pet sitter to take care of our cats. 

Our cats are indoor/outdoor cats.  They relieve themselves outside, but rarely go more than 100 feet from the house.

My best guess is that Kookies went outside to use the bathroom and was attacked by a predator.  However, the pet sitters sent us photos of the cats every day, and Kookies looked depressed and was hiding in the basement.  It is possible that she thought that she had been abandoned, and wandered off.

Thanks.