A French security official says a man who allegedly attacked three soldiers with a knife had been sent home by Turkish authorities last week after flying in on a one-way ticket.Turkey is a transit point for extremists from Europe to join up with the self-proclaimed Islamic State of Iraq and al-Sham (ISIS), fighting in Syria and Iraq.Police detained Moussa Coulibaly and a suspected accomplice on Tuesday after the attack on the soldiers in front of a Jewish community center in Nice.Border police had flagged Coulibaly to their Turkish counterparts on January 28, who promptly returned him home, the French security official said on condition of anonymity because she wasn't authorized to speak on the record.French authorities, however, were unable to turn up enough evidence against Coulibaly to open a legal case against him.