Istanbul police seize over 550 Byzantine, Roman coins from taxi

Doğan News Agency has reported that Turkish police seized 553 coins dating back to the Byzantine and Roman period inside a plastic bag held by a passenger in a cab, in Istanbul on May 16
(Istanbul police seize over 550 Byzantine, Roman coins from taxi Hurriyet Daily News ):

 Police security teams stopped a suspicious cab in the main bus terminal in the Bayrampaşa district and conducted searches inside the car. The passenger was detained during the search after police found a total of 553 coins from the Byzantine and Roman eras, as well as four rosaries and three colored stones belonging to the same periods. Police also conducted searches at a store belonging to the passenger, as well as at Istanbul’s Grand Bazaar, finding another two ceramic plates, 50 cylinder seals of different sizes and colors, five metal rings, two metal seals, five coins, five metal objects and a cross.[...] The detained passenger has been released by police pending an investigation on charges of “violating the law on protecting cultural and natural properties.”

I wonder what makes a taxi cab 'suspicious' - apart from carrying a coin dealer, that is.