That's not how technology works.

Edit: For clarity, because your downvote tells me I hurt your feelings for challenging your worldview... any nitwit with a laptop can obfuscate their identity and location with any number of free or paid services in seconds. I could be sitting in a police station making online threats over their wifi, and they wouldn't be able to find me. It's really that fucking simple. So the specific argument of "if it was just a normal person, we would know who he is..." is blown out of the water. Sorry that hurts your fee-fees.