A German teenager arrested in the Republic of Ireland over a hoax bomb threat on a transatlantic passenger jet has been released without being charged, police said on Tuesday. The 19-year-old student was arrested under Ireland's Air Navigation and Transport Act on Monday after a note was found in one of the Delta Air Lines Boeing 767's toilets saying a bomb was onboard during the flight from Frankfurt to Atlanta, Georgia. After the discovery of the note, the aircraft was diverted to Shannon Airport where it was searched by police and bomb disposal experts before being declared safe. The man was arrested after police questioned, fingerprinted and took handwriting samples from all the passengers on the flight. Although free, Irish police told CNN that files on the student were being prepared for the public prosecutor.