Under section 196A of the Criminal Law (Codification and Reform) Act, a person can be convicted as a co-perpetrator of murder even without directly inflicting the fatal blow, provided the State proves: (1) the accused was present at or in the immediate vicinity of the crime scene in circumstances which directly or indirectly implicate them in the commission of the crime (s196A(2)(a)); and (2) the accused had the requisite mens rea, namely intention, knowledge, or realisation of a real risk or possibility that the crime would be committed (s196A(1)). Presence at a violent crime scene with a weapon, coupled with conduct discouraging intervention and encouraging the assault, is sufficient to establish common purpose liability. The conduct of the actual perpetrator is deemed to be the conduct of every co-perpetrator. For sentencing purposes, murder is committed in aggravating circumstances under s47(4)(a) when weapons are used, gratuitous violence is employed, or it constitutes a gang murder, even if the specific factors in s47(2) and (3) are not present, as s47(5) and the Criminal Procedure (Sentencing Guidelines) Regulations 2023 extend the list of aggravating factors. Once aggravating circumstances are found, the mandatory minimum sentence of 20 years imprisonment applies unless exceptional circumstances justify departure.