Record contained sufficient evidence to support defendant’s conviction on charge of aiding and abetting firearm use during attempted armed robbery of post office, where witness testified that she heard defendant’s accomplice state that he had gun and saw accomplice point gun that looked like Cobra .380. Fact that witness also stated that she was not positive that object was firearm, and that it could have been well-made replica did not require different result. Also, although Dist. Ct. gave improper jury instruction that allowed jury to theoretically convict defendant on evidence indicating that defendant may not have learned of gun’s existence until time of attempted robbery, said error did not require reversal, since videotape of incident confirmed that armed robbery had been pre-planned, that defendant gave no indication of surprise once accomplice brandished gun at witness, and that instead of withdrawing from attempted robbery upon accomplice’s brandishing of gun defendant continued in his attempt to rob post office. Additionally, prosecutor did not commit Brady violation by withholding detective’s personnel file from defendant that contained prior incidents of police misconduct, since evidence of any prior misconduct contained in said personnel file would not have allowed jury to find that fingerprint evidence gathered by detective that linked defendant to charged offense was unreliable.