limits of permissible retaliation

وَلَا تَقْتُلُوا۟ ٱلنَّفْسَ ٱلَّتِى حَرَّمَ ٱللَّهُ إِلَّا بِٱلْحَقِّ ۗ وَمَن قُتِلَ مَظْلُومًا فَقَدْ جَعَلْنَا لِوَلِيِّهِۦ سُلْطَـٰنًا فَلَا يُسْرِف فِّى ٱلْقَتْلِ ۖ إِنَّهُۥ كَانَ مَنصُورًا

And do not kill the soul [i.e., person] which Allāh has forbidden, except by right. And whoever is killed unjustly - We have given his heir authority, but let him not exceed limits in [the matter of] taking life. Indeed, he has been supported [by the law].