Important supply lines of morphine base and heroin to the Sicilian Mafia were set up in the late 1970s and early 1980s after Cosa Nostra members Pietro Vernengo and Gaspare Mutolo shared prison cells in Italy with the Turkish trafficker, Yasar Avni Mussullulu, and the Singapore-born Chinese, Koh Bak Kin. Sicilian judges estimate that between 1981 and 1983, Mussullulu alone supplied two Mafia individuals with two metric tons of morphine base for the sum of US$55 million after which he disappeared from circulation and his supply line to Italy ceased.