A MOTHER wept yesterday as she told an inquest how her baby died from a massive drug overdose after his godfather mistook a bottle of the heroin substitute methadone for cough mixture. Cheung Yuk-king, 34, said the tragedy happened when she entrusted her son Fung Ting-pong to Leung So, 84, for a few days. The one-year-old baby had a slight fever and she had left some pink medicine in the fridge for him. But Ms Cheung, a former drug addict, said there was a second bottle in the flat containing methadone. The jury returned a verdict of accidental death after Mr Leung admitted he may have dosed the baby with the heroin substitute by 'a terrible mistake'. It is not known how much Ting-pong was given, but doctors said five millilitres would be enough to kill a baby. Outside court, Ms Cheung revealed she was so racked with guilt over her son's death she had immediately given up heroin. 'I'm not a drug addict now. I did the wrong thing,' she said, tears streaming down her face. 'If I had not been an addict this would never have happened. I blame myself.' The accident happened on December 17 last year, while Ms Cheung was serving a week in jail for fighting. Mr Leung had agreed to look after her son at his flat in Shui Ping Wai Estate, Yuen Long. Ms Cheung said: 'There was only one bottle of medicine in the refrigerator and I marked it anti-fever medicine in his presence. 'The anti-fever medicine bottle was pink and the bottle of methadone was a greenish colour. 'When I was released from prison I went to Mr Leung's home. He said he had given the child some herbal tea - nothing else was said. But I had some doubts because I noticed a bottle of methadone was on the table and half of it had been used up. Mr Leung said he thought it was anti-cough medicine.' At first Mr Leung denied he could have given the methadone to the child. He claimed an addict called Tai Kou, who was staying in the flat, must have administered the lethal dose while he was out shopping. But Coroner Warner Banks said: 'This story about Tai Kou giving the child the medicine comes to me as a bit of a surprise. 'The police carried out a full investigation and according to their report, it was you who had given the child the medicine and it was done very much as a terrible mistake.' Mr Leung again insisted he could not have been responsible for the mix-up. But the baby's godfather repeatedly contradicted himself about what he had or had not seen Tai Kou doing. Mr Banks said Mr Leung's new evidence made it impossible to finish the inquest without calling Tai Kou as a witness. As he was about to adjourn the hearing he asked Mr Leung once more if it was possible he could have accidentally given Ting-pong the medicine. He added: 'It's not being suggested you in any way set out to harm this child, but it is being suggested you possibly, purely by a genuine mistake, gave him methadone thinking it was the proper medicine. 'If that was the case it's a genuine mistake and a tragic accidental death and that would be the end of the matter.' Mr Leung finally replied: 'It is possible.' The inquest heard there were two other people in the flat at the time, decorator Ng Kwok-hung, 38, and labourer Wong Yun-tim, 35, who were due to be called as witnesses. But coroner's officer William Tam said they had vanished. Ms Cheung, who is divorced with a five-year-old son, left court in tears with Mr Leung.