It was a killing spree that sent a cold chill down the spine of New York, teasing baffled cops with a trail of riddles that lay beside the bodies of innocent victims.
Now, David Berkowitz - the twisted murder known as 'Son of Sam' - is the subject of a new Netflix documentary examining the dark mysteries behind the case that sickened America.
Humiliatingly caught after receiving a parking ticket, the Brooklyn-born criminal confessed to the murder of six people and wounding seven others in the city during the late 1970s.
His deranged letters, which spoke of a man called Father Sam urging him to "go out and kill", made him a national fascination, spurred on by Berkowitz's insistence that he was driven to the attacks by a demonic dog.
However, the new four-part series, The Sons of Sam: A Descent Into Darkness, explores the controversial theory that he did not act alone.
From ties to a Satanic cult to confusion over police sketches and another shocking death, here are the enduring mysteries about the case that sparked New York City's biggest ever manhunt.
'Satanic cult' that terrified New Yorkers
Initially dubbed 'The .44 Calibre killer' due to his choice of revolver, Berkowitz was deemed to be a paranoid schizophrenic by psychiatrists assisting the police during their year-long investigation.
He had left a number of notes for cops and journalists ranting about the depraved "gutters" of New York City and his fear of Father Sam.
"He beats his family. Sometimes he ties me up to the back of the house," he wrote in one letter.
"Other times he locks me in the garage. Sam loves to drink blood. 'Go out and kill', commands father Sam."
Yet the mystery grew further as investigative journalist Maury Terry compiled research suggesting that Berkowitz was not the sole culprit behind the series of deaths, but rather part of a Satanic cult.
Around the time of the killing spree, residents near New York's Untermyer Park had reported witnessing strange chanting and torch flames waved inside the woods.
In 1976, a number of carefully mutilated German Shepherd bodies were discovered there by police in an aqueduct.
Following his arrest, Berkowitz fuelled the flames by suggesting that some of the murders had been carried out by a cult he had joined in 1975.
"I was at more or less all of them," he said, before later backtracking on the statements.
"I did not pull the trigger at every single one of them. And I believe the police know that."
While his claims have been dismissed by the NYPD, the theory that there was more than one killer was backed by several high-profile figures in the case, including Queens District Attorney John Santucci and police investigator Mike Novotny.
Gruesome deaths of alleged 'accomplices'
Mysteriously, a number of the people Berkowitz claimed had a hand in the murders came to gruesome, untimely deaths shortly after his arrest.
He accused neighbour Sam Carr, who owned the black labrador used to 'control him', of being the "high official of the Devil's Legion' and a key member of the cult along with his two sons, John and Michael.
In 1978, John was found in his girlfriend's apartment after dying from a rifle shot to the face, deemed to be suicide.
A year later, Michael was killed in a drunk driving accident, despite having historically been teetotal.
In an interview with Terry, Berkowitz named both Michael and John as two of his accomplices, claiming that Michael injured two in a 1977 shooting, while John had also injured two teens the year before.
Berkowitz insisted that the two men had been murdered in a cover-up by the cult, before later distancing himself from the claims.
His theory, though, was reportedly similar to that of John's girlfriend, who is said to have told police she believed he was killed in relation to the Son of Sam investigation.
Police sketches didn't match killer
In the midst of the desperate manhunt, police released four sketches of the suspected killer.
However, when Berkowitz was finally captured, many were left questioning why he appeared to bear little resemblance to the portraits.
In the 1976 shooting he attributed to John Carr, witnesses reported seeing a young blonde man - a description that didn’t match Berkowitz, but did bear a resemblance to John.
William F McCormack, the police officer who drew one of the sketches of the Son of Sam, provided a simple explanation, insisting he was only working with the barest of descriptions.
“If I give you a pinch of salt and say, ‘Go bake me a cake—don't come back without a cake.’ What are you going to do?" he said.
"You need other ingredients but you just don't have them.”
Barbaric murder of teen by security guard
Increasingly obsessed by the prospect of cult involvement, Terry's theories eventually became a source of frustration to police.
By the time he died in 2015, many of his beliefs had been discredited, though friends argued his investigations into other murders proved he was often right.
One such case was that of Arlis Perry, a 19-year-old found dead in 1974 in a ritualistic murder bearing signs of the occult.
Terry believed that the killing at Stanford University, California, was carried out security guard Steve Crawford, before DNA evidence conclusively saw him convicted.
He also believed that the murder was somehow tied to the same Satanic cult behind the 'Son of Sam' case, though was unable to prove any firm evidence.
Speaking to the documentary, a former detective and friend of Terry says: "Of course, the [NYPD] had to say he was just a conspiracy nut, and sometimes I thought he was too.
"But the fact is, he was right more times than he was wrong."
'Missed opportunity' to stop Son of Sam
One of the lead reporters on the Son of Sam murders was Steve Dunleavy, a journalist for the New York Post.
Dunleavy later revealed that there may have been an opportunity to stop the killer in his tracks.
He said that, following Berkowitz's arrest, he had spoken to a "slightly nutty old man", Sam Carr.
Carr revealed that the killer had had regularly written to letters to his family, on one occasion complaining about their dog, Harvey.
He claimed Harvey had even been shot by Berkowitz and the bullet was still inside the dog.
"The cops said they never heard a complaint from Sam Carr," Dunleavy said - though Carr insisted he had.
If the bullet did in fact exist, the identity of 'The .44 Calibre Killer' may have been revealed far earlier in his debauched mission.
