Canadian Criminal Law/Defences/Abandonment

General Principles
Abandonment requires that there be a "change of intention on the part of the accused and, where practical and reasonable, a timely communication of the accused’s intention to abandon the common unlawful purpose".

Where group have jointly planned to commit a rape and murder and the accused assisted in the initial part of the illegal plan but then leaves part way through does not abandon the offence and can still be convicted of murder.