Serial killer David Berkowitz left people in New York living in fear for an entire year, killing six and injuring another seven during his terrifying spree.
But he couldn't resist sending bizarre notes to journalists and police officers, mocking them about future attacks - but they would ultimately lead to his arrest.
Berkowitz indiscriminately travelled around its neighbourhoods, shooting innocent people at random in the summer of of 1976 and into 1977.
He dubbed himself the Son of Sam, a chilling nickname that stuck, and came up with a truly bizarre motive for the attacks.
Berkowitz claimed he had been possessed by a demon, which had infested the body of his neighbour's dog, Harvey.
The cold-blooded killer insisted he was simply following the demon's instructions.
Harvey the dog, Berkowitz told police, belonged to his neighbour, Sam.
Berkowitz admitted in some of his chilling letters to police that he was a "monster" - but that he was not in control.
In one twisted note he said: "I am deeply hurt by your calling me a woman hater. I am not.
"But I am a monster. I am the Son of Sam. When father Sam gets drunk, he gets mean.
"He beats his family. Sometimes he ties me up to the back of the house.
"Other times he locks me in the garage. Sam loves to drink blood. 'Go out and kill', commands father Sam."
It was these notes that finally helped detectives track him down, and provided the evidence they needed to send him down for his despicable crimes.
Berkowitz had been adopted as a child by a Jewish couple and he has been described as having a "troubled" childhood.
He developed an obsession with starting fires and in his bizarre diary, which was found after his arrest, he claimed he had started almost 1,500 in New York.
Friends and family described him as a bully and his adoptive dad told him his birth mother had died when he was born - a lie.
He managed to find his birth mother when he was discharged from the army, which he described as "wonderful".
But the lie coloured much of his life.
Berkowitz said: "Looking in retrospect, that characterised much of my life.
"I struggled a lot with depression as a child and obsessions with death because I thought I deserved to die."
Then, when he was still only a teenager, his adoptive mother passed away.
The pair had been extremely close and Berkowitz struggled to cope.
He said: "When you lose someone that you love is a sense of mourning.
"I tried to put it out of my mind. I was carrying around a lot of guilt. I was carrying around a lot of shame that I deserved to be punished.
"I can’t explain those things. Maybe I was angry at God and then, well, my birth mother and then, of course, my adoptive mother too. You know I found it very difficult."
By the mid-1970s, struggling with the fact he was an illegitimate child, Berkowitz started committing a series of increasingly violent crimes.
On Christmas Eve in 1975 he tried to commit his first murder - but it went very badly wrong.
Using a hunting knife, Berkowitz stabbed two women.
Tragically one has still not been formally identified while the other was Michelle Forman.
She survived but her injuries were serious - and Berkowitz was never suspected.
And when an old pal from the army bought him a .44 caliber Bulldog gun for Berkowitz, it was the beginning of a sinister obsession.
On July 29, 1976, Berkowitz carried out his first murder.
Two friends, Donna Lauria and Jody Valenti, were chatting in a car when Donna opened the door.
A menacing man appeared out of nowhere and Donna was startled.
It was Berkowitz, who pulled his gun from a paper bag, bent down into the car and pulled the trigger.
Donna was killed instantly while Jody was shot in the leg. As quickly as he had appeared Berkowitz fled.
While Jody survived, she could not describe the killer in any detail, simply saying he was white, in his 30s with short, curly, dark hair.
Three months later, Berkowitz struck again, employing an almost identical tactic to his first killing.
Carl Denaro and Rosemary Keenan were again chatting when the vehicle "exploded".
Carl had been shot in the head and had to have a metal plate fitted to his skull, although both survived.
Neither had seen their attacker.
Just a month later, Donna DeMasi and Joanne Lomino were talking on the front porch of Joanne's home after they had been to the cinema.
The two teenagers saw a dark haired man appear out of the darkness in military fatigues.
He started to ask them a question but before he finished, pulled out a gun and shot both victims once.
Despite being shot in the neck, Donna's injuries were not life-threatening.
However, Joanne had been shot in the back and was left paralysed for life after the terrifying incident.
Berkowitz's next strike would lead to his second murder in January 1977. Christine Freund and John Diel were sitting in their car after a trip to the cinema.
They were planning on continuing with their night out when their car was hit by three gunshots,
John desperately drove off and had suffered minor injuries but Christine was been shot twice and died in hospital a few hours later.
Her death was the first time police started to link the shootings.
Less than two months later Virginia Voskerichian was walking home from college when Berkowitz again appeared out of nowhere.
The 19-year-old tried to use her textbooks as a shield but they were useless against the bullets and she was killed.
Police were now certain the shootings were linked and held a press conference and a fever of fear gripped the city.
In April Alexander Esau and Valentina Suriani were again sitting and talking in a car when they were both shot twice.
Valentina was pronounced dead at the scene while Alexander died a couple of hours later in hospital.
He was unable to describe their attacker before he passed away.
But it was after this murder that Berkowitz first penned his sinsiter nickname by leaving a note at the crime scene, which was signed Son of Sam.
After describing himself as a monster, the letter read: "Papa Sam keeps me locked in the attic, too.
"I can't get out but I look out the attic window and watch the world go by. I feel like an outsider.
"I am on a different wave length then everybody else - programmed to kill. However, to stop me you must kill me."
Police had the letter analysed and a psychologist determined that whoever was behind the killings was likely suffering from paranoid schizophrenia and thought they were possessed.
But this was just the first of Berkowitz's notes.
He also wrote to Daily News columnist Jimmy Breslin, with the words 'blood and family, darkness and death, absolute depravity, .44' on the envelope.
In it Berkowitz said: "Hello from the gutters of N.Y.C. which are filled with dog manure, vomit, stale wine, urine and blood.
"You must not forget Donna Lauria and you cannot let the people forget her either.
"She was a very, very sweet girl but Sam's a thirsty lad and he won't let me stop killing until he gets his fill of blood.
"Please inform all the detectives working the slaying to remain. Please inform all the detectives working the case that I wish them the best of luck.
"Keep 'em digging, drive on, think positive, get off your butts, knock on coffins, etc.
"Upon my capture I promise to buy all the guys working the case a new pair of shoes if I can get up the money. Son of Sam."
The letter was published in the New York Daily News, with Breslin urging the killer to hand himself into police.
But Berkowitz's murder spree was far from over - he was preparing to kill again.
Almost a month after sending his first letter to police, Berkowitz targeted Sal Lupo and Judy Pacido as they also chatted in a car.
Three shots were fired into the vehicle.
Sal was shot in his arm while Judy was hit in the head, shoulder and neck. Amazingly, both victims survived but had not seen their attacker.
However, witnesses close by reported seeing a dark haired man close to the scene.
Despite police increasing patrols in the areas where the killer had been active previously, he changed his location for his final attack in July, 1977.
While they were sitting in a car, Stacy Moskowitz and Robert Violante were kissing when Berkowitz appeared out of nowhere and fired four gunshots into the vehicle.
Both were shot in the head and while Robert lost an eye, Stacy died from her injuries.
This time, though, someone had managed to get a close look at the man who turned out to be the killer.
Cacilia Davis was walking her dog and saw Berkowitz walk past, he stared at her, and as she went on her way she heard gunshots nearby.
But she was so terrified it took her four days to tell police what she had seen.
Officers checked all cars that had ticketed close by and Berkowitz's was among them.
Police waited outside to arrest him - and for a search warrant to search his flat and car - on August 11, 1977.
Then he appeared outside the apartment and Detective John Falotico made the decision to approach Berkowitz's car.
The .44-caliber Bulldog gun was foud in the car and Berkowitz admitted instantly that he was "Sam".
Just 30 minutes after officers started grilling him, Berkowitz confessed to his murder spree but insisted his neighbour's black Labrador, Harvey, was possessed by an ancient demon and had told him he had to kill.
He was examined by three medical professionals who deemed him competent to stand trial and in May, 1978, pleaded guilty to all the shootings.
He was jailed for 25 years for each murder, all to be served consecutively, and has been in prison ever since.
He is described as a "model" inmate but has refused to ask for his release at any of his parole hearings.
