What is the ruling when one perpetrator claims their initial wound healed, but the co-perpetrator denies it and the heir denies the first perpetrator's claim?

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If the first party claims healing and the co-perpetrator denies it, and the heir chooses Qisas, the denial by the co-perpetrator is irrelevant because the original act mandates killing. If the heir accepts Diyah, the statement of the first party, upon taking an oath, is accepted, and no more than half the Diyah is incumbent upon him. If the heir denies the first party's claim, and the first party swears an oath, the heir may execute him because the presumption is against the claim of healing.