customs officials arrested a nigerian man at don muang airport yesterday for allegedly trying to smuggle for kilogrammes of heroin out of the country. a total of 4.9 kilos of heroin worth about 1,000 million baht if silk abroad, was contained in nine paper envelopes, a customs official said. each envelope was hidden in a briefcase,the official said. the nine briefcases were allegedly brought to the airport by osita charles 26, who presented to have them as samples of briefcases to be sold in nigeria, the spokesman said. he had intended taking a singapore airlines flight scheduled for 2.50 p.m. to the netherlands and nigeria via singapore, customs official said.netherlands and