When you wrote "Why on earth would any random killer find a person that has an 80 pound pit bull on their side?" This made me wonder: maybe the dog wasn't by her side when she was attacked. Is there any chance that she briefly let Bowie off leash inside the park? I know some people do this, even in areas where it doesn't seem prudent for dogs to be off leash. Maybe when she was initially targeted - which if this was a random targeting, could have happened with extreme speed as a blitz attack - the killer didn't initially register that she had a dog with her? If the dog came running up a few seconds later to engage with him, he might have killed the dog and then returned to her to inflict more damage. Just a thought - without knowing her usual routines with the dog, it's hard to know if this is a possibility.