In asking a private security firm to investigate instead, Weiner won’t be able to prove his innocence by obtaining logs from Twitter showing where his account was accessed from. Twitter says it requires a subpoena or court order to hand over such information. A subpoena or court order would have to be initiated by police or the FBI, not private detectives…

Sites such as Twitter usually keep logs of which Internet addresses are used to access an account, sort of like an online guestbook. It doesn’t contain names, but these numerical Internet Protocol, or IP, addresses identify computers and phones…

One obstacle is that websites don’t have to keep logs of Internet addresses, and those that do keep them for differing amounts of time. Twitter and yFrog didn’t respond Thursday to questions about how long they keep Internet address information.