Turkish police on Friday arrested two Tunisian nationals at Istanbul\'s Ataturk airport, who were allegedly involved in the killing of U.S. ambassador to Libya, Shems FM reported quoting Turkish Kanal D channel. It said both Tunisians were trying to enter Turkey with fake passports, and Turkish police is questioning them. Libya has arrested 50 people involved in the killing of U.S. ambassador to Tripoli, Christopher Stevens, who along with three of his staffers were killed when the U.S. consulate building in Benghazi in eastern Libya came under attack on the night of Sept. 11.