Onubogu and Anor v. The State (1974) 9 S.C. 1, 20: the Supreme Court opined that where in a criminal case, one witness called by the prosecution’ contradicts another prosecution witness on a material point, the prosecution ought to lay some foundation, such as showing that a witness was hostile, before they can ask the court to reject the testimony of one witness in preference for the evidence of the discredited witness. It is not competent for the prosecution to discredit one and accredit the other.
WHO IS A TAINTED WITNESS?
A tainted witness has been classified as one who is either an accomplice or by the evidence he gives, whether as a witness for the prosecution or defence, may and could be regarded as having some purpose of his own to serve. See: Ishola v. The State (1978) NSCC 499 at 509.
— Iguh, JSC. Oguonzee v State (1998) – SC.131/97