Boy In A Box 2

This theory concerns a foster home that was located approximately 1.5 miles (2.5 km) from the site of the body.

In 1960, Remington Bristow, an employee of the medical examiner's office who doggedly pursued the case until his death in 1993, contacted a New Jersey psychic, who told him to look for a house that matched the foster home. When the psychic was brought to the Philadelphia discovery site, she led Bristow directly to the foster home.

Upon attending an estate sale at the foster home, Bristow discovered a bassinet similar to the one sold at J. C. Penney. He also discovered blankets hanging on the clothesline that were similar to the one in which the boy's body had been wrapped when they discovered him. Bristow believed that the boy was the son of the stepdaughter of the man who ran the foster home, and that they disposed of his body so the stepdaughter would not be exposed as an unwed mother.

However, the police established that all the foster children were accounted for, and a reexamination by police investigators confirmed that the family were likely not involved.

In 1998, Philadelphia police lieutenant Tom Augustine, who was in charge of the investigation, and several members of the Vidocq Society (a group of retired policemen and profilers), interviewed the foster father and the stepdaughter (whom he had married). The foster home investigation was closed.

Another theory was brought forward in February 2002 by a woman identified only as Martha, or "M", accusing her mother of acquiring and killing the child. Police considered her story to be plausible but were troubled by her testimony, as she had a history of mental illness. She said that her mother and father purchased Joseph from his birth parents in the summer of 1954, after which he was beaten to death and his body left abandoned inside a box outside of town. Police were unable to verify her story. Neighbors who had access to Martha's house during the stated time period denied that there had been a young boy living there and dismissed Martha's claims as "ridiculous."

Forensic artist Frank Bender developed a theory that the victim may have been raised as a girl. The child's unprofessional haircut, which appeared to have been performed in haste, was the basis for the scenario, as well as the appearance of the eyebrows having been styled. In 2008 Bender released a sketch of the unidentified child with long hair, reflecting the strands found on the body.

In 2016, two writers, one from Los Angeles, California (Jim Hoffmann) and the other from New Jersey (Louis Romano), believed they had discovered a potential identity from Memphis, Tennessee, and requested that DNA be compared between the family members and the child. The lead was originally discovered by a Philadelphia man (who introduced Romano and Hoffmann to each other) and was developed and presented, with the help of Hoffmann, to the Philadelphia Police Department and the Vidocq Society in early 2013. In December 2013, Romano became aware of the lead and agreed to help the man from Philadelphia and Hoffmann to obtain the DNA from this particular family member in January 2014 – which was sent quickly to the Philadelphia Police Department. Local authorities confirmed that they would investigate the lead, but said they would need to do more research on the circumstances surrounding the link to Memphis before comparing DNA. In December 2017 Homicide Sgt. Bob Kuhlmeier confirmed that DNA taken from the Memphis man was compared to the Fox Chase boy, and there was no connection.

Joseph Augustus Zarelli was originally buried in a potter's field. In 1998, he was reburied at Ivy Hill Cemetery in Cedarbrook, Philadelphia, which donated a large plot. The coffin, headstone, and funeral service were donated by the son of the man who had buried the boy in 1957. There was significant public attendance and media coverage at the reburial. City residents keep the grave decorated with flowers and toys.

The large headstone when first installed contained the words "America's Unknown Child", with a plaque underneath reading, "Heavenly Father, Bless This Unknown Boy". On January 13, 2023, which would have been Joseph's 70th birthday, a new memorial containing his full name and image was unveiled, along with the addition of his name to the existing headstone.