On March 1, 1932, the 20-month-old son of aviator Charles Lindbergh was kidnapped for ransom from the family's Hunterdon County mansion, in a crime that stunned the nation and remains the subject of doubt and speculation more than 80 years later.
Now the PBS science program NOVA weighs in on the case, relying on behavioral science and forensics in an attempt to solve it.
But as in past efforts, the program, scheduled to air 9 p.m. Wednesday on WHYY TV12, offers answers to some questions but raises others as well.
The hour-long documentary focuses mainly on the analysis of John E. Douglas, a former FBI agent and one of the agency's first criminal profilers.
Douglas says his investigation proved to him that Bruno Richard Hauptmann, who was executed for the crime, did not act alone.
In addition, Hauptmann and his accomplices deliberately killed Charles Lindbergh Jr. because they did not want to care for a toddler while waiting to collect their $50,000 ransom, Douglas said.
The child, whose decomposed body was found in woods 4.5 miles from Lindbergh's home two months after the abduction, died of a massive skull fracture. There has been speculation since that the boy died in a fall, perhaps when he was being carried down a ladder from his second-floor bedroom.
Supporting the contention that the child was intentionally killed, John Butts, North Carolina's former chief medical examiner, tells NOVA the toddler died from a blow, possibly with a hammer, to the right side of the head, puncturing the skull, and causing a fracture on the left side.
Douglas spends some time exploring the possible role in the kidnapping of John Knoll, a German immigrant whose name has not been linked to the case until recently.
In Cemetery John: The Undiscovered Mastermind of the Lindbergh Kidnapping, Robert Zorn recounts the story based on a recovered memory told to him by his father Eugene Zorn.
Robert Zorn, in an interview with the Inquirer in July, said his father was a 15-year-old boy in 1931 when he accompanied Knoll, a neighbor, on an outing to Palisades Amusement Park.
There, John and his brother Walter met with another German named Bruno, and Eugene Zorn heard them talking about Englewood, where the Lindberghs lived at the time while their East Amwell, Hunterdon County, home was being built.
Cemetery John was the name given to the person to whom a Lindbergh intermediary, John F. Condon, passed the ransom money in a Bronx cemetery a month after the kidnapping,unknown to the police.
Condon later provided a description police used to create a drawing of the ransom taker and said the man had a fleshy lump on his right thumb.
Douglas agrees with the book's findings that John Knoll matches the drawing and notes other photographs of Knoll show he has unusually large thumbs.
An expensive first-class trip by ship to Germany that Knoll took with his wife during Hauptmann's trial also raises suspicions, Zorn and Douglas agree.
Douglas says he would consider Knoll a prime suspect worthy of further investigation, but that the existing evidence would not be enough to charge him.
Mark Falzinicq, archivist at the New Jersey State Police Museum, and Sargur N. Srihari, a computer scientist, poke some holes in the theory implicating Knoll.
Falzini said Hauptmann never used the name Bruno, preferring to be called Richard and even signing his name Richard Hauptmann.
Srihari said a computer analysis of both Knoll's and Hauptmann's handwriting shows it is unlikely either wrote any of the ransom letters supposedly sent by the kidnappers. During Hauptmann's trial, prosecution experts testified that the handwriting was his.
NOVA said New Jersey denied a request to test the glue on the envelopes from the ransom notes for possible DNA.
Douglas rules out theories that Lindbergh was involved in the kidnapping because his son suffered a defect that he, as a supporter of eugenics, could not accept.
The former FBI agent said Lindbergh's deep personal involvement in the investigation, even acting on his own without police knowledge, was more reflective of the aviator's true nature as a take-charge individual than someone who would harm his child.
But that involvement, Douglas acknowledges, hampered the investigation more than it helped it.
One thing is clear, Douglas said. "Someone absolutely got away with money and murder."