premise: Turkish police confiscated 160 kg of heroin stashed in two trucks in an operation in Turkey's largest city of Istanbul on Friday, the semi-official Anatolia news agency reported.
  Four suspects were arrested in the operation in Avcilar district of Istanbul, facing charges of dealing illicit drugs.
  In another operation on the same day, gendarmerie officers, acting on a tip-off, found 30 kg of heroin hidden in a car in Baskale town of Van province in eastern Turkey, Anatolia said.
  The report said that the gendarmerie forces received help from a sniffer dog in finding the heroin in Baskale, adding that a full- scale manhunt is underway to arrest the owner of the car.
  Turkey is on a key transit route for gangs smuggling drugs from Asia and the Middle East to markets in western Europe.
  
  In 2005, Turkish security forces seized 6,663 kg of heroin, 140 kg of morphine, 34 kg of opium, 6,002 kg of hashish, 40 kg of cocaine, some 1.23 million captagon pills and 5.76 million ecstasy pills, official figures showed.
   What led to the finding of the heroin in Baskale?
hypothesis: acting on a tip-off