I hope you are correct - it will be easier to solve this. But soot could come from being in a vehicle or other building that contains soot - chimney, furnace work, etc. If you've ever changed even your hot water tank pipes, they are often filled with soot - so it doesn't have to be this house, only. But again, I hope they could start narrowing and focusing.
I am thankful that someone (the dad) at least is giving us something to go on. Poor Somer had so many men in her life in her short time ... the comment about she was a hugger always bothers me.