How do you get someone's name from their IP address for harment claims?

The IP traces to a verizon hub in Machusetts, but that's as far as I can go. The police think i'm an idiot for even bothering with this, and verizon (india only though) claims they "don't have such information". Im sure they have it once the FBI is looking for al queda or kiddie ... so how do I get it?