H.E. Pennypacker said:
How do you know they're all the same guy if he's using different IPs every time?
Well, most often, people use either broadband modems or dial-up modems (the general public uses either of these two), which one does he use? Since he spends so much time on the Internet, its probably broadband. In that case, the IP won't change until the ISP decides to change it (may take a long while...weeks or months).
If he uses dial-up, which would be shocking, his IP would change every time he logs on. That's because dial-up users from a single ISP all get a group of IPs. A good example is AOL. People wouldn't be able to identify you specifically if you were using AOL because others are probably using the same IP. However, AOL has other ways of identifying people.
