I'm a journalist--not a computer scientist--typically the header would contain the sender's IP--however seeing as they are all 10.x.x.x I'm guessing he masked himself through tor or something... As much as I would love to, I don't think I can provide you much more. Than a phone number and e-mail address--thanks for anything that you can do or anyone you can refer me to--cost is pretty irrelevant, I'm determined find this person for the principle of it.

Thanks,
Makksik