I'm amazed PJ are refusing to hand over DNA - that's appalling.
That said it could be anyones blood and could have been there for months and there isn't much. It was also not evident with the naked eye so would have to have been cleaned up which would take time. Nosebleeds, cut knees, shaving cuts etc all very normal
Personally I don't think a small child could draw blood from a adult male. Not enough strength and very easily overpowered.
My grandaughter is the same age of MM and she could easy scratch, bite enough to draw blood and has done

MM was feisty also so I think would prob react if she felt in danger.
I'm not sure if a small child would run away from CB either. Nor make it far if they tried. When small kids wake up frightened don't they usually scream rather than run. Or get up and go to find their parents? Personally I think it would take more cognitive reasoning to run and hide than a three year old would have
That's just my opinion. I think if he spoke nicely about going to find mummy and daddy she'd have gone willingly. She was a very young child.