Joel Greenberg, a chief witness in the sex trafficking case against Florida Rep. Matt Gaetz, appears to be working with investigators trying to determine if the 41-year-old Republican had intercourse with a 17-year-old girl while serving in Congress. “I can confirm that Mr. Greenberg is cooperating in a congressional investigation,” Greenberg’s attorney Fritz Scheller told the Daily News on Friday. “The nature of the investigation, as well as the subjects of the inquiry, are questions better left for congressional investigators to answer.” Scheller clarified to The New York Times the investiga...