In a conviction for attempted murder under section 21(2) of the Criminal Code, two critical stages must be affirmed: mens rea and principles of fundamental justice. Mens rea, which refers to the mental state or intent behind a person's actions, is pivotal in cases of attempted murder. It establishes whether the accused had the necessary intent to kill or cause serious bodily harm, which is essential for determining criminal liability in such severe offenses. The prosecution must prove that the accused had the specific intent to commit the crime. Principles of fundamental justice are also crucial in ensuring that the legal process respects the rights of the accused and adheres to the concepts of fairness and due process. These principles safeguard against arbitrary or unjust convictions and ensure that the laws applied align with the broader values of justice in the legal system. The other options provided, including witness testimony and physical evidence, while important, do not directly relate to the specific requirements of establishing guilt under section 21(2). Likewise, aiding the police and feelings of remorse may be relevant in other contexts but are not foundational to the legal thresholds necessary for proving attempted murder. Standard of care and negligence pertain to a different area of law, generally concerning civil liability rather than criminal intent.