Well, as C. Lee said...ask psychologists and criminal psychologists that question I'm sure they can answer just fine. Most serial killers start out by torturing and killing animals, especially cats.
I mean lets face it. She didn't throw that cat in the garbage can to have a laugh about it. Give me a break. She lured it in, petted it, then opened the can and tossed it in. Then she walks away really fast and she wasn't laughing that's for sure.
She didn't know she was being video taped and so she had to make something up. She wasn't even sorry for it, haha. "I'm sorry but..it was just a cat!". Yeah, to most people it is just a cat. It is just an animal. However, to a lot of people in this country and in most other countries like England...cats and dogs become members of the family. Might as well tossed one of their kids in the trash can while your at it. There goes a laugh or two, right?