Serial killers have captured the minds of society ever since the term was coined in the strange 70s. There was a rash of violent crimes that the populous hadn't ever seen the likes of except in small, condensed pockets. The most likely theory about why there were more serial killings isn't that there were more serial killers or anything like that, but that they were more visible after getting more coverage in the press.
Maybe slasher movies had a hand in that, or maybe they were created to help the collective psyche of civilization in coping with the unthinkable scenario that had befallen them.
10 Rillington Place
10 Rillington Place is a crime thriller that came out in 1971, starring a young Richard Attenborough. The film documents the British serial killer John Christie, who was active during the early 40s and into the early 50s. He killed upwards of 8 victims and was executed by hanging. Originally, a tenant in the building he resided in was charged with 2 of his murders, who were the tenant's wife and child. After being convicted of the murders, John Christie's fellow tenant was sentenced to death by hanging and then Christie's murders came to light 3 years later. In the 2000s, it was finally owned up to and the law admitted they had made a mistake.
The Ancines Woods
This film is partially based on the life of Manuel Blanco Romasanta, who was generally considered to be Spain's first serial killer. The film itself is slightly played-up considering its inclusion of the concept of lycanthropy, a common early and superstitious explanation for the serial killer phenomenon.
He admitted to the murder of 13 people but claimed that he couldn't be held responsible since he was a victim of the werewolf curse. He was convicted of the murder of 9 people but was likely responsible for over 20.
Burke & Hare
Burke & Hare is a horror film from the 1970s that focuses on the Burke & Hare killings that took place in 1828. There were about 16 murders over a period of ten months. They were involved in the murders for the sake of making money by selling them to Robert Knox, who would use them for dissection during his anatomy lectures. They were part of a wide movement usually engaged in by people who were in terrible poverty. The "Resurrection Men" were people who would go around the law, and usually break it, to find corpses to sell.
Deranged
Deranged is a 1974 Canadian horror film that is highly fictionalized but loosely based on the life and times of American serial killer Ed Gein. The film was very well-reviewed other than the fact that it didn't do the most incredible job at adapting the events it's based on. While Ed Gein didn't really commit too any actual murders, a lot of his exploits have been pulled from when creating a whole swath of horror movie slashers. Ed Gein is most famous for creating grotesque memorabilia from the corpses of his victims, and of people located in a nearby graveyard he would sneak into for the acquisition of the bodies.
The Honeymoon Killers
The Honeymoon Killers is a crime thriller released in 1970, directed by Leonard Kastle. Originally, the film was going to be directed by Martin Scorcese but he was fired. The film is based on real-life murderers from the 40s, Raymond Fernandez and Martha Beck who were known as "The Lonely Hearts Killers". They were only convicted of one murder, most definitely committed 2 more, and are suspected by many of having killed upwards of 20 over the course of 2 years. They had a very specific modus operandi that has been featured in tons of horror movies, which was that they would take out ads in lonely-hearts sections of local newspapers.
The Tenderness Of Wolves
The Tenderness Of Wolves is a 1973 German Horror film directed by Ulli Lommel, about the life of serial killer and cannibal Fritz Haarmann. Fritz was known variably as "The Butcher", "The Wolfman" and "The Vampire" of Hanover. Haarmann was executed by guillotine after the murder of 24 male children and adults from 1918 to 1924. He received his frightening nicknames thanks to the mutilation he incurred upon his victims and due to the fact that his preferred method was to bite the throats of his victims.
Texas Chainsaw Massacre
The Texas Chainsaw Massacre is a film released in 1974 directed by Tobe Hooper, who went on to direct plenty of successful horror movies like Poltergeist. The film was presented as being based on a true story, both at the beginning of the movie and in the marketing for the movie, and to a degree it was, but only in that it was also based on the life of Ed Gein. The film is helped in its mission of keeping everything presented as if it's as real as possible in that its production is particularly raw and grainy.
Frenzy
The second-to-last film from Alfred Hitchcock's extensive film career, Frenzy was released in 1972. It's a story about a serial killer in contemporary Britain. The film isn't based on anyone in particular, but there's lore involved regarding other serial killers.
In one of the opening scenes of the film, the Christie murders that appeared earlier in the article are mentioned, in addition to the Jack The Ripper murders that happened in Whitechapel during the late 1800s. To prepare for the role, the lead actor studied books about Neville Heath, a serial killer who posed as an author in the British Air Force.
Halloween
Halloween is often referred to as the first slasher, despite the fact that Texas Chainsaw Massacre, Black Christmas and Peeping Tom had already been released. These films were very influential on the genre, but it really wasn't until Halloween or maybe Black Christmas that they came together in a way that might officially be called a slasher. Halloween took tons of cues from both Psycho and Black Christmas. The film wasn't exactly based on any serial killer in particular, but many of the familiar parts of a serial killer's psyche are there.
The Bird With The Crystal Plumage
The Bird With The Crystal Plumage is a movie that comes to us from Italy, directed by master of horror Dario Argento, who's also famous for working on Suspiria. This movie is one of the first to come out that can be properly described as Giallo which is a genre based on yellow crime books that were popular in Italy. The word Giallo actually translates to yellow in Italian. Some of these crime/mystery novels were based on true stories of murder and mayhem, but some of them were fiction. The film is about an American writer who witnesses the attack of a young woman in an art gallery and then does his best to get to the bottom of the murders that happen surrounding him.