To this day, they and many others can rattle off the countless intricate details of the case as if they were as fresh as the 6 oclock news.
A La Salle College student stumbled across the body on Feb. 25, 1957, in a wooded area on property owned by the Sisters of the Good Shepherd, near Susquehanna and Verree roads.
The nuns operated a home for wayward girls. Investigators suspected that the young man had driven to the site to spy on them.
The dead boy was naked, wrapped in a distinct woven blanket and left inside a cardboard bassinet box from JCPenney. At first, the college student didnt report the finding. A priest convinced him to notify authorities the following day.
It triggered the start of an investigation the scope of which Philadelphia had likely never before seen.
Officer Elmer Palmer was first on the scene, followed a short time later by Weinstein. Detectives like Lt. David Brown took up the investigation as did Bristow, working for the city medical examiner, Dr. Joseph Spelman.
Spelman ruled head trauma as the cause of death. The victim also was malnourished. It was considered a homicide from the start.
The age of the boy, the conditions in which he was found and the apparent utter disregard for his well-being in life or death by the killer or killers admittedly struck a nerve even in the most-hardened cops and criminal investigators, many of whom were also military combat veterans.
For the same reasons, they reasoned that his identity wouldnt remain a secret for too long. Someone must know who he is and what happened to him, they figured. Someone must share their pity for him.
Kelly, who among other duties was responsible for chartering an airplane to photograph the crime scene from above, remembers speaking with Brown at the time.
"He said it was one of those seventy-two-hour cases. They had no doubt (it would be solved)," Kelly recalled. "It was a child. Somebody would come forward."
Nobody did. Investigators checked missing child reports from far and wide, but none matched the boy. They went from hospital to hospital, sifting through thousands of birth records and baby footprints. Still no match.
They posted the boys touched-up post-mortem portrait in supermarkets throughout the region and mailed out copies in monthly gas bills, too.
Investigators published details of the case in law enforcement journals across the country and internationally, hoping to find the missing link.
But many years, many leads and many debunked theories later, they still had nothing in the way of a name for the boy.
By necessity they moved onto more pressing matters, but a few continued their pursuit of justice for the boy, even when it meant doing it on their own time.
It was like Bristow considered the youngster a part of his own family. He even marked the anniversary of his discovery each year by placing flowers on his grave in the citys Potters Field along Dunks Ferry Road in the Far Northeast.
The grave was the only one in the field with a stone marker. Investigators had purchased it at the time of his burial. Its inscription read, "Heavenly Father, Bless This Unknown Boy."
Bristow died in 1993. In 1998, a local author and organization of law enforcement experts injected new life into the case.
Ron Avery, a longtime reporter for the Daily News, featured the case as a chapter in his book City of Brotherly Mayhem, a compilation of stories of many of the most notorious crimes and criminals in Philadelphia history.
While doing research for the book, Avery interviewed William Fleisher, a private investigator and former FBI and U.S. Customs agent who said that thoughts of the boy had "haunted" him since his own childhood when he saw the aforementioned photo while shopping with his mother.
"Certain things always triggered the memory of it," Fleisher said.
As commissioner of the Vidocq Society, a private and secretive organization of law enforcement and forensics professionals who use their vast expertise to crack troublesome cases, Fleisher endorsed the groups adoption of the case with the consent of the Philadelphia Police Department.
He contacted Weinstein, who passed away several years later.
Kelly and McGillen were chosen to lead the investigation for the society.
Detective Tom Augustine served as the liaison to the Philadelphia polices homicide division before he retired from the department last year.
Within weeks, investigators exhumed the boys remains to extract a DNA sample. They reburied the skeleton in November 1998 at Ivy Hill with a marker renaming him "Americas Unknown Child."
"This is symbolic of all of the abandoned, murdered, abused children," Fleisher said. "I always viewed it as a candle going out."
The case was featured on an episode of Americas Most Wanted and dramatized liberally on Cold Case.
In 2002, the renewed attention and persistence paid off with what Kelly and McGillen feel is the strongest explanation yet for what happened to the boy. They even got a name, but its only a partial one.
A woman from Ohio contacted them and claimed that, as a child, she lived in a Main Line home with the boy and witnessed his killing.
Her parents bought the boy on the black market and kept him hidden from outsiders in a box in the basement, she said. She knew him only as Jonathan.
The informant explained that her mother, who died in 1985, killed the boy by beating his head on a bathroom floor. That would explain the head trauma, along with the "washerwoman" effect discovered on some of his extremities. Thats the rippling of skin that occurs when its submerged in water for a length of time.
"Joe and I still believe that interview is the best thing that we have," Kelly said. "We believe it is the most valid story we have."
The statement alone wasnt enough to close the case from an official standpoint, however. Corroborating proof is lacking and so is a last name.
Bristows hunch that a one-time foster home in nearby Montgomery County held the answer could still figure into the equation, Kelly says. The man and woman living there housed as many as a dozen orphans at a time for the city.
Though none of the children there in early 1957 matched the dead boys description, Bristow returned to the house years later after the couple moved away. The contents of the home had been put up for public auction. Bristow found a bassinet like the one that would have been packaged in the notorious box.
The former medical examiners investigator went to his grave believing in a link.
Mondays service was as much recognition of the commitment to the boy shown by Bristow and his successors as it was a memorial to the child himself.
"In his own deceased persona, (the boy) has taken on a great deal of meaning for those of us working on the case. We feel we have known him personally," McGillen said.
"In death, the little boy has had more love and affection than he ever had on planet Earth," Kelly said.
Reporter William Kenny can be reached at 215-354-3031 or bkenny@phillynews.com