He—may Allah sanctify his soul—was asked:

A man saw another man kill three Muslims during Ramadan and lick the sword. The ruler had been unable to apprehend him to carry out the prescribed punishment. The witness later encountered him somewhere but was unable to seize him. May he kill the aforementioned man, who committed these unlawful killings? If he kills him, will he be rewarded or held liable for his death?

He replied:

If he was a highway robber who killed them to take their property, he must be put to death and may not be pardoned. If, however, he killed them for a personal reason, such as a dispute or enmity between them, then his fate rests with the victim’s heirs: if they wish, they may put him to death; if they wish, they may pardon him; and if they wish, they may accept blood money. He may therefore only be killed with the permission of the other heirs.

As for a highway robber, one view requires the ruler’s permission. Whoever knows from the circumstances that the ruler has authorized his killing may kill him on that basis. For example, someone may know that the authorities are seeking him to put him to death and that his execution is obligatory under Islamic law. Such a person knows that they authorize his killing. When putting him to death is obligatory, whoever kills him is rewarded for doing so.

He—may Allah have mercy on him—was asked:

Two men were involved: one held a man while the other struck him, leaving his hand paralyzed. What is the ruling?

He replied:

Praise be to Allah. There is disagreement on this matter. The stronger view is that both are subject to retaliation in kind if it is applicable; otherwise, both are liable for the blood money. And Allah knows best.