A blackmailer who was accused of terrorising prostitutes with serial sex attacks dating back 20 years has been cleared of rape for the eighth time. Keung Chi-shing, 45, claimed he had been framed because prostitutes were angry with him for extorting money from them. He originally faced 23 charges of rape, robbery and attempted robbery going back to 1979 and involving nine women. Prostitutes had come forward to make allegations after publicity surrounding his arrest in April 1996. But one after another, these allegations were either dropped or thrown out, or he was acquitted of them. He was convicted of four blackmail charges, which he admitted in January 1997, and is serving five years' jail for those crimes. The prosecution offered no evidence on the last outstanding rape charge yesterday. The alleged victim now admits she used a description provided by another woman to help pick Keung out of an identification parade. His barrister, Robert Forrest, said after the Court of First Instance hearing: 'Justice has at last been done.' Six charges had been dropped before Keung first went on trial in January 1997. He was left facing 17 allegations, including eight rapes on five women. Keung was accused of tying up, gagging and blindfolding his victims. One woman alleged she had been raped five times in different flats. But 10 of those charges were then thrown out during the trial by a judge because of 'tenuous evidence'. At the end of the trial Keung was found guilty of raping two women and sentenced to a total of 14 years imprisonment. But these convictions were quashed on appeal and two new trials ordered. A jury cleared him in the first trial and the second trial did not go ahead because the prosecution offered no evidence yesterday. Mr Justice Frank Stock ordered that a not guilty verdict be entered in relation to the charge of raping a woman who is now 46. Keung had admitted blackmailing four women by demanding money and telling them he was 'one of the local bullies'. Mr Forrest, during the last trial, had told the jury the alleged victim 'and her sister prostitutes were fed up with the fact he was menacing them into giving him money'. He argued that Keung had been framed.