Judges 20:12

And the tribes of Israel sent men through all the tribes of
Benjamin
Meaning the families of Benjamin; for as sometimes a tribe is called a family, ( Joshua 7:17 ) so a family is called a tribe; and there were ten families in the tribe of Benjamin, according to the number of his sons, the fathers of these families. ( Genesis 46:21 ) , which being numerous and powerful, and consisting of men of courage, and expert in war, thought themselves a match for the ten tribes of Israel now assembled, who sent one out of each tribe, very probably ten in all, upon this errand; for they judged it most advisable, before they went to war with them, to try to get the offenders, delivered up to justice, and so prevent the shedding of blood of either side; and the rather, as there were none of the tribe of Benjamin at this assembly, and which indeed might give them reason to suspect they meant not to join with them in an amicable manner in this affair: however, they were willing to try peaceable methods first:

saying, what wickedness is this that is done among you?
not that they were sent to inquire what the crime was that was committed, that was fully known; but by putting the question in this manner, their design was to aggravate it, and to put the men of Benjamin on considering how great it was, what an enormous sin it was that was committed, and that among them; and therefore it lay upon them, either to punish the perpetrators of it themselves or deliver them up to them to be punished according to the common law of Israel.