Where accused persons raise defences of alibi in a murder case, the state bears the onus of disproving those defences, but the accused must fully disclose the alibi defence to enable proper investigation. Where an alibi defence is not fully disclosed and is disproved by credible evidence, and the state proves beyond reasonable doubt that the accused persons, acting with common purpose, assaulted the deceased and threw him into a mine shaft, continuing with their conduct despite the real risk or possibility of causing death, they are guilty of murder under section 47(1)(b) of the Criminal Law (Codification and Reform) Act. Accomplice witness evidence must be treated with caution and requires corroboration, but such evidence is not to be automatically discarded (applying State v Chohan 1981 (2) ZLR 237 SC). Minor variations in witness accounts regarding details of an assault occurring at night during a beer drink where torches were prohibited do not necessarily undermine the credibility of evidence establishing the accused's presence and participation.