Detectives are trying to identify two suspected killers by examining fingerprints left on a can of flammable liquid used in an arson attack at a Tsing Yi flat that left two men dead. Chief Inspector Tsang Fan-kwong, of the New Territories South regional crime unit, said the can was one of the main clues in the case in the absence of a motive so far. Chan Chi-sing, 20, and Cheuk Oi-ming, 44, were killed in their friend's home in Ching Yung House, Cheung Ching Estate, on Tuesday. Two suspected killers were seen fleeing the scene after the attack. Police suspect the two victims were members of the Wo Shing Wo triad society and were drug addicts. They say they had often gathered with friends in the flat. Last Friday, Chan was among five people arrested in connection with a theft case when officers raided the dwelling. Results of post-mortem examinations conducted yesterday showed that the two men suffocated to death.