Philadelphia police detectives have finally solved the department’s oldest unsolved homicide case after identifying a young victim known as “America’s Unknown Child.”

The child, also referred to as the “boy in the box,” was revealed to be 4-year-old Joseph August Zarelli through DNA forensics technology.

Zarelli was a child victim whose body was found wrapped in a blanket inside of a cardboard box in February 1957. Autopsy results later found that the boy died from blunt force trauma.

According to Police Commissioner Danielle Outlaw, the case attracted “immense” public interest at the time, but no one came forward to identify the child, and the case remained a mystery for the next 65 years.

Zarelli was buried with a headstone that read “America’s Unknown Child.”

Through the diligent efforts of detectives and genetic genealogists, police were able to finally identify the boy.

“For 65 years, the story of America’s Unknown Child has haunted this community, the Philadelphia Police Department, our nation and the world,” Outlaw said in a news conference on December 8. “Despite the fact that Joseph Augustus Zarelli’s entire identity and rightful claim to his own existence was taken away, he has never been forgotten.”

Officials say the techniques used to identify Joseph can help solve other cold cases as well. Indeed, the technology used in the case — known as forensic genetic genealogy — was critical in solving other famous cold cases, such as the Golden State Killer case.

Outlaw said the result “brings hope that there will never again be an unidentified victim of homicide in the city of Philadelphia.”

Captain Jason Smith of the department’s homicide unit said that Zarelli’s body was exhumed in 2019 after it was determined forensic techniques could make headway in the case.

Forensic genetic genealogy company Identifinders International worked closely with Philadelphia police to track down relatives in the child’s maternal family by comparing the boy’s DNA with DNA of relatives on a genetic database.

Eventually, investigators were able to identify Zarelli’s mother and obtained the birth records of the boy, which then led them to the boy’s father. Both mother and father are now dead, according to police, but Zarelli’s siblings are still alive.

Those working on the case said the search for the killer is still ongoing, and the case is far from over.

“We have our suspicions as to who may be responsible, but it would be irresponsible of me to share these suspicions as this remains an active and ongoing criminal investigation,” Captain Smith said.

“We may not make an arrest. We may never make an identification (of the killer). But we’re going to do our darndest to try,” Smith said.

“This announcement only closes one chapter in this little boy’s story while opening up a new one. This is still an active homicide investigation, and we still need the public’s help in filling in this child’s life story,” Outlaw declared.

There is a $20,000 reward out for information leading to an arrest and conviction of a possible suspect.

Ivy Hill Cemetery officials said Zarelli’s gravestone would finally have his name etched in.