The ringleader of a criminal syndicate was found guilty yesterday of operating a brothel in flats he rented from an auxiliary police officer. Cheng Chiu-kin, 59, was convicted of one count of conspiracy to live on the earnings of prostitution. Cheng rented subdivided flats from auxiliary officer Lam Man-yim, 48, and Lam's girlfriend, Stella Lung Chi-wai, 38, to operate a brothel in Kwun Tong from January 2009 to October 2011. The brothel operation began when Lam bought four units between 2008 and 2011, registering one under Lung's name. He subdivided the space and rented the cubicles to Cheng through Ho Hing-tong, 43, another defendant. The vice den was run by Ho and other defendants - Yau Wai-ming, 48, Wong Wah, 47, and Liza Ki Pui-ling, 55 - who worked as pimps and housekeepers, the court heard. Other co-defendants, including Lam, pleaded guilty at their trials last month to conspiracy to living on the earnings of prostitution and related charges. Lam testified against Cheng. Delivering his ruling, District Court Judge David Dufton questioned the defence argument that Lam's credibility was weakened by his testifying against Cheng. The defence claimed he might have given false information, both to win a lighter sentence for himself and Lung, and because he was frightened by Cheng's alleged triad links. Dufton said there was sufficient evidence to prove Cheng's guilt beyond a reasonable doubt. In a 2011 raid on the brothel's management office, the Independent Commission Against Corruption found six cigarette butts carrying Cheng's DNA. Keys to the flats, including those to the management office, were found at Cheng's home. His phone contained a record of calls to and from the other defendants who helped run the brothel. Immigration records showed he had travelled to the mainland with Ho and Yau. "Although the immigration records only showed that the defendants had connections with each other, it can be inferred from all other … evidence that [the ringleader] took part in the prostitution conspiracy," Dufton said. The ICAC investigated the case initially because police officers were accused of accepting free sexual services from the prostitutes in return for turning a blind eye to the vice den. But no police officers were arrested. Sentencing for Lung is set for April 9 and for the others next Monday. Lam, who also owns a plastic factory, joined the auxiliary police force in 1988.