Under which circumstances the court should not rely on recovery of knife recovered as per S 27 of Evidence Act?

[Educator]

Circumstances (f), (g) (h) and (i) - Re: Disclosure statements, consequential discoveries and their connect with crime.71. With regard to the making of disclosure and the consequential discoveries/recoveries, according to the prosecution on 23.09.2000 the two Accused made disclosures assuring recovery of weapon of assault and blood-stained clothes worn by them at the time of commission of murder