What happens if each heir names an unknown person in addition to a known accused?
Chapter on Qasamah (Oaths regarding murder)
Al-Mughni
Book of Blood-Money (Diyyāt)
Primary text
If one heir states, "He killed Zayd and another person I do not know," and the other states, "He killed Amr and another person I do not know," the Qasamah is not established according to the apparent position of Al-Khiraqi because the accusation must be against one person, and they did not agree on one accused party. The right is established only through the oaths of all parties concerning the point of agreement. However, Abu Bakr, Al-Qadi, and Al-Shafi'i rule that the Qasamah is established because there is no explicit mutual denial; it is possible that the unknown person to one is the known person to the other. Each heir swears fifty oaths against the person they named, and they are entitled to one-quarter of the blood money. If they later identify the unknown person as the one named by the brother, each swears another twenty-five oaths, building upon the brother's oath, and is entitled to an additional quarter.
Supporting text
There is an alternative view that the first oath taker swears only twenty-five oaths because he is swearing only for the half he is entitled to, analogous to when his brother swears alongside him. If one heir later claims that the person he previously did not know is different from the person named by his brother, the Qasamah they swore is nullified because the contradiction invalidates the doubt, and each must return the portion of the blood money taken. If only one heir contradicts his brother, only the Qasamah of the contradicting heir is voided, not that of the one who remained silent.