A 63-YEAR-OLD grandmother was mugged and robbed in the cubicle of a public toilet, an inquest heard yesterday. Lee Tai-kiu told a relative of the assault, but refused medical treatment despite sustaining numerous bruises. About one hour later she went shopping and collapsed at a bus-stop. She was taken to hospital but died a short while later, Coroner Warner Banks was told. The coroner's jury returned a verdict of death by natural causes. Pathologist Dr Wong Hon-man said bruises and abrasions were found about her head consistent with blows from a blunt implement. Because the injuries were found scattered all over the head they were more likely to have been caused by assault rather than a simple fall, Dr Wong said. He pointed out that in the absence of associated brain injuries the head injuries were not fatal by themselves. He said there were indications that Lee had been suffering heart disease which was sufficient to cause death under the circumstances. ''In view of the time lapse of about one hour [between the assault and the collapse, there was] unlikely to [be] any direct link between the alleged robbery and assault and the death in this case,'' Dr Wong said. It was possible that the stress associated with the incident might have accelerated or precipitated death due to the heart disease, Dr Wong said. The cause of death was recorded as heart disease. Lee, who lived in Shuen Wan, Tai Po, died on May 11 at the Prince of Wales Hospital. The deceased's niece, Lee Koon-chea, told the court that the pair had met as usual for morning tea. The deceased left at about 10.30 am, saying she was on her way to the Shun Tak home for the aged. Thirty minutes later, the pair met up again where Lee Tai-kiu said she had been assaulted and robbed in a toilet cubicle in Fu Shin Street, Tai Po. ''She said she was assaulted by a young man who entered the cubicle and then covered her mouth and hit her,'' Ms Lee said. The witness told coroner's officer Llewelynn Mui that the deceased had never complained of heart problems.