CANNIBAL killer Jeffrey Dahmer was “shy” but likeable at school before going on his infamous murder spree, an ex-classmate has revealed. Dahmer, dubbed The Milwaukee Cannibal, drugged, raped, murdered, dismembered and ate 17 men and boys from 1978 to 1991. Jeffrey Dahmer is one of the most notorious serial killers in criminal historyAFP He strangled and stabbed them in a bloodfest that ended only after a would-be victim overpowered him and led cops to his fly-infested flat in Wisconsin. But one of his old school pals insists he was “quiet and shy” at school and said he actually “liked him”, The Mirror reports. John Backderf has spent years trying to come to terms with the horrific crimes committed by his childhood friend. He eventually went on to write a book about his relationship with the serial killer, titled My Friend Dahmer. Dahmer is pictured as a teenager during his high school years The deranged cannibal went on to rape, murder and eat 17 men and boysPolice Handout The book has now been turned into a film by the same title, which hit cinemas yesterday. And its author, now 58, insisted Dahmer was “not always a monster”. He said: “The Jeff I knew had committed no crime. “So yes, he was a monster – but not always. I liked him.” John Backderf was pals with Dahmer at high school before his killing spreeGetty A still from new film My Friend Dahmer, which was based on Backderf’s bookMGM Dahmer committed his first murder just three weeks after graduating at 18. He lured 18-year-old hitchhiker Steven Mark Hicks to his house, before bludgeoning and strangling him. He later dissolved the body in acid, crushing the bones and scattering them in nearby woodland. This was the start of a killing spree so horrific it would catapult him to global notoriety. A blood-soaked mattress is removed from Dahmer’s apartment by cops in 1991Milwaukee PD Dahmer is pictured in court in 1991 after his 13-year killing spree was endedAP:Associated Press When cops raided his flat 13 years later they found three human heads in his fridge, along with skulls, torsos, organs and hands scattered around his flat and more than 70 Polaroids of mutilated bodies. But Backderf insists Dahmer was just “another sad kid with problems” and the horror could have been avoided if adults had reached out to the troubled teen. He recounted how the young Dahmer was quiet when he first met him at the age of 12, but became more outgoing at high school. He started disrupting class with bizarre pranks like pretending to have seizures – to the amusement of his group of pals, who would egg him on. Most read in news TROUBLE BREWING Camilla 'spat out her tea at Harry's "ridiculous" suggestion to heal rift' TITLE ROW Charles 'may bar Archie & Lilibet from being prince & princess over Harry's book' PROF MICHAEL CLARKE I'm a war expert - Putin WON'T use nukes, he has another sinister plan 'DRAMA GONE' William and Kate 'relieved when Meghan and Harry left for the US' FREE AT LAST 5 Brit POWs including one who was held for 5 months freed by Russian captors BACK IN THE HEIR Harry & Meghan ‘returned to LA yesterday’ to be reunited with kids Backderf recalled how Dahmer spoke fondly of those days from his prison cell as “the best time of his life” because he had friends. He added: “I don’t think it’s any coincidence he began to kill when school ended.” He told how he felt “numb” years later when he heard the horrific details of his former pal’s crimes. Backderf said: “With the snap of a finger my entire personal history changed. “All these silly things we had done in high school, just like that they became very sinister.” But he insists he never felt sympathy for Dahmer, who was battered to death in prison by another inmate in 1994, saying: “He made the choice to kill.” We pay for your stories! Do you have a story for The Sun Online news team? Email us at tips@the-sun.co.uk or call 0207 782 4368. You can WhatsApp us on 07810 791 502. We pay for videos too. Click here to upload yours.