Here's an update on that case involving the 17-year-old girl, and her dog being beheaded. Someone was arrested:
http://www.cnn.com/2007/US/03/23/dog.head.ap/index.html and this, which has a few additional details:
http://www.chron.com/disp/story.mpl/bizarre/4656928.html Notice the part at the end about donations pushing the $2,500 reward to $20,000. Maybe that helped, but either way I'm glad they've got a suspect.