Where multiple accused (particularly police officers) participate in concealing a crime committed by one or more among them, and the principal offender cannot be identified, all can be convicted as accessories after the fact to the principal crime under the Gani principle. The actual perpetrator(s), by participating in the cover-up, becomes an accomplice to the others' crime of being accessories. For police officers, deliberate failure to report a crime known to them, combined with acts to conceal it (such as moving a body and making false statements), constitutes the unlawful act required for conviction as an accessory after the fact when done with intent to help the perpetrator evade justice. This duty arises from their statutory obligations as police officers, distinguishing them from ordinary citizens who generally have no duty to report crimes.