The sexting case with the underage girl in North Carolina is the Federal case. I'm not sure if New York's criminal statutes would cover interstate communications like that.
If the victim was in North Carolina, New York could claim jurisdiction based on Weiner’s presence in Manhattan when he committed the crime. He was physically in NYC, used a phone with origination in NY area code, billing, cell tower, etc. He is a permanent resident of NYC and likely made his contacts with the victim from his home address. That’s more than enough to give NYPD valid claim that he violated NY State law. North Carolina and the Feds also have claims that are valid, but nobody has taken Weiner into custody and formally charged him. Possession being 9/10 and all that...GRAB HIM UP!