The point of my comment was to highlight the fact that the article presents information that contradicts the picture. According to the picture, the child was decapitated. Decapitation is removing the head from the body. If that were the case, the questions posed by the commenter would be reasonable. If I saw my child beheaded, I would absolutely chase down the killer. But the child wasn't decapitated.

The victim wasn't killed in front of the parents as the picture suggests, the victim was attacked in front of the larents. Perhaps they were tending to the injured child? That seems like a reasonable thing to assume. That's certainly what I would do.