I noticed at the close of the book of Judges that once again there is the sentence, "At that time there was no king in Israel; everyone did what was right in his own eyes."
Pretty much a recurring theme throughout the book, unfortunately, especially here in the last three chapters. Had everyone not done so - what they believed in their own eyes to be right - then perhaps we would not have had folly upon folly heaped on after the initial wicked act of the men of Gibeah (who raped a poor helpless concubine to the point of death in chapter 19), whereupon it would result in a war claiming as much as 75,000 lives from among the various tribes of Israel and especially the Benjamites.
This may be my personal opinion, but I think one such folly may have been the second Levite man (the first one being from Micah's and the Danites' story in the previous two chapters) seizing upon his concubine and literally cutting her to pieces to send as physical proof of the crime committed against her by the men of Gibeah, to the other Israelite tribes. I think it was a bit of an overreaction, and unless I missed it, Scripture doesn't even seem to say that she was already dead for sure after the rape, but close to death. So the Levite husband might have actually killed her in the process, instead of, well, trying to bring her medical help. On top of that, I believe he was the one who gave her up to the men of Gibeah anyway to save himself in the first place. I honestly don't know why, in the case of giving her up to Gibeah, he couldn't have at least tried to save her from succumbing to the trauma and wounds of her rape, and simply called leaders from the other Israelite tribes to come to him and see for themselves the proof of the Benjamite city's heinous crime against her, if the Levite wanted justice. Rather than killing her (assuming she had not already died from the trauma) and sending pieces of her corpse in the "mail" to them.