Wiener Boy was sexting a minor (child pornography) out of state so that brought the Feds into the mix. Feds issued the subpoena. Here’s a link for you - I excerpted the key sentences:
http://www.washingtontimes.com/news/2016/sep/22/anthony-weiner-investigated-federal-prosecutors-se/
CNN reported Thursday afternoon that the U.S. Attorney’s Office in New York has issued a subpoena for cell phones and other records belonging to Mr. Weiner, a former Democratic U.S. representative who looked destined to be New York mayor.
“The FBI and the New York Police Department have opened preliminary investigations,” CNN wrote, about charges that surfaced earlier this week in the Daily Mail.
thank you.