I'm writing about a world that predates most modern forensic techniques, and I am looking for some old-fashioned methods of sleuthing that would have been available at around the 1850-1900.
In one scene, there is a massive explosion that results in a lot of blood and dead bodies. I'm looking for a plausible explanation for how my protagonist, who was present (and bleeding) at the scene of the crime, was tracked back to her home a day after the fact after no one knew she had been there and no one saw her leaving.
I need a reality check on whether dogs could have possibly been used to do this back then, specifically:
Could a dog follow the trail of a person who had some of their own blood on the bottom of their shoes, even if it was a day old?
Could a dog pick out the scent of a single person in the rubble of a collapsed building with ~30 bleeding/dead people around, or would so many scents confuse it? In other words, could a dog deduce the scent of a single person even if it were mixed with so many others, or would it have to have smelled them all separately?
What about if it already knew their smell, say by smelling something they touched? Would it be able to tell that the scent of a certain human corresponded to the scent of that person's blood? (i.e. Does your blood smell like "you"?)
If not, is there maybe something other than blood that a dog might be able to track better? Something that could have been available (but not too common) roughly around Victorian England?
The solution needn't necessarily be dog related--it's just all I can think of at the moment that wouldn't be anachronistic! Non-canine solutions from that time period equally welcome.
Edit: Dogs are way more impressive than I thought they were! Now I'm glad I picked my username.