PHILADELPHIA (WPVI) — Philadelphia investigators will provide an update Thursday on one of the city’s highest-profile unsolved mysteries.

Police say through detective work and DNA analysis, officers have finally identified the child known as the “boy in the box.”

The body of the little boy was found in a cardboard box on the side of Susquehanna Road in Fox Chase back in 1957. The boy was nude, malnourished and fatally beaten.

His remains had never been identified until now. The case remains Philadelphia’s oldest unsolved homicide.

Bill Kelly took the young victim’s fingerprints at the scene back in 1957. His family says he never stopped trying to find out the boy’s identity or assailant up until his death.

“He was one of the first on scene that fateful day. He never forgot about that image. I mean how could you? … He was the fingerprint expert on scene. Those fingerprints were ingrained in his mind his whole life, and when he closed his eyes in his mind that’s what he saw,” said Kelly’s grandaughter, Jessica Greene, who knew him as pop-pop.

“I was thinking my father would be so happy … so happy,” said Kathleen Kelly Greene, who is Jessica’s mother.

When news spread last week that Philadelphia police would hold a news conference revealing the boy’s identity, it sent shock waves through the community. It hit home to the children of the people who worked the case and had hoped to see a resolution in their lifetime.

Kym Durham is a psychic medium in South Jersey. She has…