Twelve members of the ground staff at Beijing Capital International Airport and three South Korean students will face trial in Beijing for allegedly organising a smuggling ring that sneaked 13 people out of the country in two years, according to mainland media. The airport employees, who included a security guard and Air China Cargo and tarmac shuttle bus drivers, were working for a Hong Kong 'snakehead' prosecuted in a separate case, the Beijing Times reported. The South Koreans are accused of helping the operation by clearing check-in and security checks, then handing their boarding passes to the illegal immigrants. The ring was exposed in December 2007 when border security officers at the airport found that four Chinese men boarding an Air China flight to Vancouver did not have visas for Canada and the names on their boarding passes did not match their passports. The illegal immigrants, natives of Changle, Fujian , said they each paid a snakehead 500,000 yuan (HK$567,300) to go to Canada to work. They were transported out to their flights on a cargo vehicle and given boarding passes by four Singaporean passengers who arrived at the same time on the tarmac shuttle bus. The border officers suspected airport workers were involved because the four men reached the plane in an Air China Cargo vehicle and did not go through any security checks. The vehicle's driver later confessed that the smuggling operation was organised by Zhu Yonglin , an airport corridor security guard, and Air China Cargo driver Mi Changshan at the behest of a snakehead in Hong Kong. The four Singaporeans were hired by the Hong Kong snakehead. A police investigation found the practice started in 2006, when the Hong Kong snakehead gave Zhou Zhuang , an employee of Beijing Immigration Security Check Station, tens of thousands of yuan to help smuggle people. Over two years, Zhou recruited 12 other airport ground staff. The group made eight attempts to smuggle people using the method, but only half were successful. Security guards would monitor if immigration officers were checking visas before passengers boarded the plane. The operation would be called off if immigration officers were around, but the plan eventually backfired when the ring failed to notice officers on the last run.