You would think so, as generally one thinks if there is enough trauma to kill a child there should be blood.
Like in
Andrew's death:
http://louiselarsen.blogspot.com/2011/01/today-little-boy-was-run-over-and.html
However, there really isn't blood in a lot of these cases. Out of the 5 toddlers we have had run over in our area... only one involved a significant amount of blood. That one was a baby, a truck and a busy main 45MPH street... not a driveway.
It would totally depend on the situation... but for example, a 2 year old who was run over at the chest or abdomen, would likely be bleeding internally. Bruises/abrasions outside but no real blood.
The head may be different, even if the major damage is inside... even minor head wounds bleed a lot. It is the internal injuries though, that kill them.
I also factor in that someone will often pick up and move the child so fast that no blood is actually left where the accident occurs. This has occurred a couple of times here. Where there was a bloody nose, or bleeding from the head... but the child was moved so quickly that the blood didn't ever hit the ground.
I think the scenario in this case is highly unlikely.... However, the parents brought up the alcohol so I wanted to mention it. If someone hit Joshua, he wasn't on the ground for very long... and probably was put onto a jacket or something in the vehicle. IF there was any blood at all.
This first case is near me.
4 year old - massive internal injuries, broken bones
http://www.ksl.com/?nid=148&sid=4067523
There is no sign of blood in either of these situations either, I can think of several other ones as well... but these are closer to Joshua's age:
2 year old - 11 year old driver
http://www.kmph.com/Global/story.asp?S=14383269
2 year old - head trauma
http://www.cbs19.tv/Global/story.asp?S=14369854