Prevention of Corruption Act, 1988–Secs. 7 & 13(1)(d) r/w. Sec. 13(2)–Conviction–Testimony of witnesses–Establishment–PW 1 is the only witness of alleged demand and acceptance–He admitted in cross-examination that his version regarding the demand made by the appellant on various dates was an afterthought–PW 2 & 3 are not the witnesses of demand–PW 4 admitted in cross-examination that appellant had served a memo to him alleging that he was careless in performing his duties–Held, the conviction of the appellant is liable to be set aside.