I've only just become aware of this case (I apparently live under a rock) and it's one of those cases that really does make you shudder. All murders are horrific but some are so vile and involve such overkill that it's unfathomable any human being could do that.
I haven't caught up on all the information yet, but I've seen a few comments questioning the likelihood of the perpetrator choosing to randomly attack someone with a dog.
It reminds me to some degree of the Rachel Nickell case from the UK about 30 years ago. She was out walking in a busy park in broad daylight, with her two-year-old son and her labrador-greyhound mix dog. The man who killed her chose her at random, stabbing her almost 50 times and sexually assaulting her. Nobody saw or heard it happen despite people being nearby. Her son was physically unharmed, and so was the dog, presumably because it didn't try to fight the attacker. It took almost 15 years for LE to find Rachel's killer.
The dog interests me in this case, because LE appear to have said so little about Bowie. We know he was found fairly near the park entrance with multiple stab wounds. But would he have been killed no matter what, or was he only killed because he tried to protect KJ? Also, did he run around at all after being stabbed, or were his wounds immediately incapacitating causing him to collapse on the spot; information about possible blood trails would be useful. LE presumably have that information and will have a good idea of exactly how and where the attack took place, where it commenced, where it ended, etc., but from what I've seen so far they don't appear to have released many details.
And one other thought... was Bowie on or off his lead? Because if he was running off his lead, it's possible an attacker wouldn't have known Bowie was there until after the attack started.