Self-inflicted stab wounds are a hard sell...especially if you collapse your own lung.
Sorry but it doesn't pass the smell test: the first person you kill is the adult male. MacDonald's wound was described by ER physcians as "small and clean" and his lung was not fully collapsed.
MacDonald's retrial "evidence" rests almost entirely on the recanted testimony of one person; appeals courts do not generally grant retrials on this basis because recanted testimony is notoriously unreliable, MacDonald has probably been given extra leeway because of the notoriety of his case. His shouldn't be. He's a murderer and the evidence against him is overwhelming.