In the first season of Cold Case, there were two young children whose shocking deaths viewers were made to process, but it was the second child death that likely hit the hardest. "The Boy in the Box" was the 14th episode of the show and took us back to the 1950s, then made us watch as a seemingly harmless scene – a young man chasing a rabbit into the woods – dumps us into one of Cold Case's darkest moments: finding a dead baby in a box.

The gutwrenching flashback leads us to present time, where on Cold Case, we watch Lilly Rush do what she does best, piecing together the clues and at last identifying the child as Arnold Culliver. The episode even ends with Lilly at the Arnold's funeral, with his ghost appearing to indicate his unfinished business has concluded.

There's only one problem with Cold Case's depiction of this famous case, though, which is based on real events that transpired in Philadelphia in 1957: The case of the boy in the box, dubbed "America's Unknown Child," was never actually solved in the real world. In fact, just last year, the genetic genealogist who identified the Golden State Killer, Barbara Rae-Venter, began working on this particular cold case, like a modern day Lilly Rush, with a plan to use DNA profiling (they dug up the body and removed enamel from the boy's tooth in 1998). The hope is at last to perhaps put a name to one of Philadelphia's most tragic cases and one of America's oldest mysteries.

The true story of the boy in the box is this: In February 1957, a cardboard box was discovered with a baby's bassinet inside, and inside the basinet, a dead child, bundled in a plaid blanket and determined to be between the ages of 3 and 7. The boy was found by a young man, just like in Cold Case, who was aware that there were muskrat traps in the area and chased after a rabbit to keep the bunny from being caught in those traps. Upon finding the child's body, the young man waited until the next day to report it to police, apparently due to a general reluctance to have contact with police at all in his life, not any foul play.

Once police did reach the scene, they did everything they could to solve the case, combing the woods with more than 270 officers and finding small items like a kid's scarf or a man's blue cap, even a white hanky with a "G" stitched on it, but all these clues pointed nowhere. Desperate, they even decided to dress the child (he was found naked) and pose him in photos on flyers, of which thousands were printed and stuffed into gas bills, hoping someone would see the photo and recognize the boy. If they did, they never came forward, but on Cold Case, they recreated the flyer (just minus the staged photo of the dead body).

So even though Cold Case showed the funeral scene for the boy in the box, the actual boy found in the real world continues to be buried in a grave marked not with his name, but the eerie moniker "America's Unknown Child." Each year, visitors drop by Ivy Hill Cemetery in Cedarbrook, Philadelphia, to leave flowers and stuffed animals, as the media still grapples with the mystery and anyone still invested in the case continues to search for answers.