By James Law
In New York City, 40 years ago, people were afraid to go out at night.
Women with brown hair would cut it short, or even dye it blonde.
Young people were urged to stay out of the borough of Queens altogether.
A serial killer was on the loose, randomly executing innocent strangers with a volley of bullets from a .44-calibre handgun.
Police weren't even sure the shootings - which terrorised the city for a year - were connected until the killer left behind a letter for them.
In a handwritten scrawl using slanted block letters, the murderer introduced himself to the world as the Son of Sam.
"I am deeply hurt by your calling me a wemon (sic) hater. I am not. But I am a monster," the letter reads.
"I am the 'Son of Sam'. I am a little 'brat'.
"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.
"Behind our house, some rest. Mostly young - raped and slaughtered - their blood drained - just bones now ... I feel like an outsider. I am on a different wave length then (sic) everybody else - programmed too (sic) kill ... I am the 'monster' - 'Beelzebub' - The 'Chubby Behemouth' (sic)."
Now, 40 years after his arrest, Son of Sam himself, David Berkowitz, has explained the "dark forces" that drove him to kill.
In an interview from behind bars aired in the US this week, Berkowitz told CBS News that he "despised" the name Son of Sam and that he believed at the time that he was serving a "demonic entity".
Berkowitz's killing spree began in the summer of 1976 when he approached two women sitting in a parked car in The Bronx after having spent the night at a disco.
As Donna Lauria, 18, stepped out of the car, Berkowitz produced a gun from a paper bag and shot her, killing her instantly. Her friend Jody Valenti, 19, was shot in the thigh, but survived.
After this initial thrill kill, Berkowitz stalked New York's residents for the next 12 months, eventually claiming six lives and leaving another seven with horrific injuries.
He seemingly chose his victims at random as they went about their daily lives. He targeted young people - usually in their late teens or twenties - often as they were sitting in their cars or walking home late at night.
As Berkowitz grew more confident he began leaving letters taunting the police and corresponding with journalists at the city's tabloids, promising more deaths.
Fear quickly spread throughout the metropolis.
Because many of the victims had long brown hair, brunettes began to cut theirs short or bleach it in the hope of escaping the killer's attention.
Although the police didn't know it, at the time Berkowitz was living in an apartment block in Yonkers, just north of New York City.
"I wasn't comfortable there. I felt very isolated," Berkowitz told CBS News.
"I didn't really have much of a social life.
"I started to get into a lot of satanic stuff, so I really was opening myself up to some very dark forces.
"There was just a battle going on inside me."
While Berkowitz takes responsibility for the murders, today he maintains that he was possessed when he went on his killing spree.
"As far as I'm concerned, that was not me," he said.
"Even that name, I hate that name, I despise that name, that moniker 'Son of Sam'.
"That was a demon. That was a demonic entity that I was serving.
"That was just a break from reality. I thought I was doing something to appease the devil. I'm sorry for it.
"I was serving him. He had taken over my mind and body and I just surrendered to those very dark forces.
"I regret that with all my heart."
Berkowitz became a born-again Christian while behind bars in the 1980s and now dedicates his life to spreading god's word.
"I'm very sorry for what happened and I wish I could go back and change things," he said.
"I draw comfort, if you can call it that, from reading about in the scriptures some of the well-known Bible characters that did very bad things and how God forgave them and God was able to use them in very special ways, very unique ways and they became what we'd call champions of the faith."
Berkowitz is serving six consecutive 25-years-to-life sentences. Because he pleaded guilty in court, he is eligible for parole, but his applications have consistently been denied.