What is the procedure if the two sons dispute who initiated the killing?
General Chapter
Al-Mughni
Book of Wounds
Primary text
If the two sons dispute which one initiated the killing, it is held that the one who killed first should be addressed first because his act was prior. Alternatively, a draw (lottery) should be held between them. This latter view is attributed to Al-Qadi and is the madhhab of Al-Shafi'i because they are equal in entitlement, necessitating recourse to a draw. Whoever kills his brother first, either by initiative or by drawing lots, inherits from him, according to the principal analogy of the madhhab, unless there is another heir. If the killer is screened from inheriting the entirety of his brother's estate, then if the killed one had an heir, the other killer inherits.
Supporting text
If one who was initially subject to Qisas pardons the other, and then the pardoned one kills the pardoner, he still inherits from him, and the Diyya due upon him is dropped. If both mutually agree upon Diyya, they settle what they equally owe, and the killer of the mother owes the killer of the father any surplus, as the blood money for the mother is half that of the father. Another potential ruling is that Qisas lapses entirely for both due to their equality in entitlement, similar to how two equal Diyahs lapse, because fulfilling one Qisas without the other constitutes injustice, rendering neither permissible.