A debt-ridden mechanic tried to commit suicide by gassing himself, but died following an explosion when he lit a cigarette, a coroner heard yesterday. Coroner Paul Kelly said Lai Li-nim, 20, had meant to end his life by inhaling LPG gas in his Yuen Long flat on July 9 last year. 'At some stage during the process, he lit a cigarette . . . and caused the explosion,' Mr Kelly said. But Lai Jo-yee, Lai's younger sister, said she and her parents believed the blast was accidental. 'I think he probably intended to kill himself, but did not realise the gas wasn't toxic enough. He might have changed his mind later and then gone to sleep,' she said. 'The next morning he lit up a cigarette which caused the explosion.' Mr Kelly returned a verdict of suicide, as Lai had deliberately disconnected the tube leading from the LPG cylinder and sealed the windows and doors of his flat. Lai, described by his mother as a cheerful and easy-going man, was involved in three traffic offences last year and owed thousands of dollars, Eastern Court heard. Lai's friend, Cheung Kwok-kwok, 24, said Lai, who earned $9,500 a month, had been in financial difficulties and had said 'in a joking manner' that he wanted to kill himself. At about 11am on the day of the incident, a severely burned Lai was found on the floor of the flat where a lighter, a metal ring and a screw were also found, the court heard. Police believed the screw was used to loosen the metal ring attaching the LPG gas tubing to the cooker. The gas which leaked from the cylinder - propane - was not toxic but could 'easily be ignited when reaching an explosive range', said government chemist Cheung Yiu-ming. Lai suffered 94 per cent burns and died from bronchial complications in Prince of Wales Hospital on July 17 last year.