Sometimes we just can't find a way to solve a crime, even using all of the modern tools we have today. Here is one such story from Listverse.
The Boy in the Box
In 1957, an unidentified Caucasian male, probable age 4 to 6 years, whose nude body, wrapped in a cheap flannel blanket, was found lying face up inside a large cardboard carton just a few feet from the edge of Susquehanna Road in Northeast Philadelphia. The body was dry and clean. The boy’s arms were carefully folded across his stomach. The finger and toenails had been recently trimmed short and neat. His hair had been cut recently – very close to the head, in a crude, hurried way, perhaps as a deliberate attempt to conceal the child’s identity. Small clumps of cut hair clung to his entire body, suggesting that someone had groomed him while he was unclothed, probably either shortly before or immediately after death. There were many bruises all over the child’s body; particularly on the head and face. All of the bruises appeared to have been inflicted at the same time. Despite recent DNA investigations in to the crime, it remains unsolved.
Seems to me that many clues were there to at least find out the identity of the poor victim.