Literature provides myriad examples of people and cultures at war or in fights, often to the death. It's pretty clear from most of these examples that people are capable of great hatred, cruelty, and violence. In literature, those are pretty common and, for want of a better word, acceptable. We don't think less of epic characters for thoroughly killing their enemies.
That changes the moment the enemy is dead, however. At that point, we see a split.
There are characters in literature who, once the enemy is dead, stop and allow whatever funerary rites are culturally appropriate, either doing these rites themselves, or allowing the dead characters family or people to perform them. Consider, for example, Hal in 1 Henry IV, treating Hotspur's dead body with respect. It's one sign that Hal has what it takes to be a real king (in an age of violence). Compare that to the ways people on stage react to the reported mutilation of the bodies of the English by the Welsh women at the beginning of the play. Think then of how vile Falstaff becomes in the moment when he mutilates Hotspur's body by wounding him in the thigh.
Or think of the beginning of "The Knight's Tale," when the mourning widows stop Theseus mid-march and ask him to make Creon allow them to bury their dead properly. Theseus immediately goes to war and defeats Creon.
These examples are from earlier English lit, of course, but world lit is full of examples: one of the basic lessons from the humanities is that you treat the dead, even of your greatest enemy, with care and respect.
So when I read about the resistance to burying the body of Tamerlan Tsarnaev, I think about how little we (as a culture) have learned one of the basic lessons of the humanities. (Here's a link to the Washington Post article. In contrast, the funeral director who's taking care of the body, and his uncle who washed and wrapped the body, these people have somehow learned that lesson.
It's not just ancient history that teaches this lesson, either. US people get rightly mad when our dead are dragged behind trucks or mutilated, too.
I wonder when we in the US became so out of touch with basic humanity?