A 4-year-old's body was discovered in 1957. Police just identified the 'Boy in the Box'.

Police in Philadelphia this week identified a boy whose body was found in 1957 and whose death became the city’s most famous cold case.

Authorities on Thursday said the boy whose body was found in a wooded area of Philadelphia’s Fox Chase neighborhood is Joseph Augustus Zarelli. Both of Zarelli’s parents are dead, but he still has living siblings, police confirmed. After his body was found, he was estimated to be between four and six years old.

Zarelli was found in late February 1957, wrapped in a blanket and inside of a JCPenney bassinet box. He was beaten to death, authorities later confirmed.

He was eventually buried in Philadelphia’s Ivy Hill Cemetery, though portions of his remains were kept for testing, officials explained on Thursday. In 2019 a court order was obtained for his remains to be exhumed for additional examination.

Zarelli’s headstone read “America’s Unknown Child.” Services were held at the cemetery each year on the anniversary of the discovery of his body.

Philadelphia Police Commissioner Danielle Outlaw departs after a news conference in Philadelphia, Thursday, Dec. 8, 2022. Nearly 66 years after the battered body of a young boy was found stuffed inside a cardboard box, Philadelphia police have revealed the identity of the victim in the city's most notorious cold case. Police identified the boy as Joseph Augustus Zarelli.

Police declined to name Zarelli’s parents out of respect for his living siblings.

Officials explained this week that modern DNA analysis and interpretation from genetic genealogists helped experts determine the boy’s identity after decades. His results were uploaded to DNA databases, and experts were first able to locate and contact relatives on his mother’s side. Authorities obtained an order for vital records of children born to the woman they believed to be the boy's mother and received his birth certificate. Through additional testing, experts were also able to determine the child’s father.

The boy was four years old at the time of his death. The homicide investigation into his death remains open.

Philadelphia Police Commissioner Danielle Outlaw told reporters on Thursday that the unsolved death has “haunted this community, the Philadelphia police department, our nation, and the world.”

“When people think about the boy in the box, a profound sadness is felt, not just because a child was murdered, but because his entire identity and his rightful claim to own his existence was taken away,” she said.

Outlaw on Thursday tweeted that “the search for justice continues,” asking people to contact officials if they do have any information on his death.

The marker of the grave of a small boy whose battered body body was found abandoned in a cardboard box decades ago in Philadelphia is seen Wednesday, Dec. 7, 2022. Nearly 66 years after the boy was found, on Thursday, Dec. 8, Philadelphia police revealed the identity of the victim in the city's most notorious cold case. Police say detective work and DNA analysis helped them learn the name of a youngster, Joseph Augustus Zarelli, who'd been known to generations of Philadelphians as the "Boy in the Box." His naked, badly bruised body was found in a wooded area on Feb. 25, 1957.

William Fleisher, the co-founder of the Vidocq Society, a volunteer group founded in Philadelphia that assists law enforcement agencies, told reporters on Thursday that investigators have worked on the case of the boy in the box for decades.

“Many of these men and women aren’t with us anymore, but I feel their souls are standing here at this moment with us,” Fleisher said at a news conference.

“Now our lad is no longer that boy is in the box," he said. "He has a name.”

This article originally appeared on USA TODAY: 'Boy in the box' identified: Joseph Zarelli ID'd in cold case death