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Two British teens were acquitted of a plot to carry out a massacre at their high school in a Columbine-inspired attack despite police evidence of the pair allegedly making explosives together.

Matthew Swift, 18, and his friend Ross McKnight, 16, were cleared of what prosecutors had alleged was a plan to slaughter students and teachers at the school in Manchester, in northwest England, on the 10th anniversary of the U.S. high school shootings.

The jury took less than an hour to deliberate at a Manchester court before reaching a verdict. It was a stunning blow to prosecutors and police, who had enlisted U.S. investigators who worked on the Columbine case to help them.

Police said they found footage of the pair making explosives together, as well as a cache of extremist literature, a bomb-making manual and sketches of the school layout at Swift's home.

Both teens shared a fascination with the Columbine killings and repeatedly alluded to plans for mass violence.

McKnight's diary referred to "the greatest massacre ever" while notes found in Swift's bedroom read: "Eric Harris, Dylan Klebold will rise again" — a reference to the teenage killers who slaughtered 12 students and a teacher at their Colorado school before committing suicide in April 1999.

Police were alerted after McKnight drunkenly called a girl he had feelings for and allegedly confessed to the purported plan, and he and Swift were arrested March 21. Detectives said they found Adolf Hitler's autobiography "Mein Kampf" and "The Turner Diaries" — a book popular among white supremacists.

But no weapons or explosives were ever found. Both teens argued that the police evidence was proof of nothing more than adolescent fantasy.

McKnight, whose father Ray is a police officer, testified that his interest in the school rampage was piqued when he saw Michael Moore's documentary "Bowling for Columbine" with other students.

He dismissed his journal entries as "intriguing nonsense" and said that he was probably angry at the time. His father Ray told jurors his son was full of hare-brained schemes.

Swift said his writings and plans, drawn up in 2007, were "naive and pathetic ways to channel my teenage angst."

"I was 16 with a vivid imagination," he told the court.

The jury took only 45 minutes to find the pair innocent. Swift breathed an audible sigh of relief as he left the witness stand, while McKnight hung his head. The most serious charge they were acquitted of, conspiracy to murder, carries a maximum life sentence.

Ray McKnight said he never doubted his son's innocence.

"We are all just incredibly relieved," he said after the verdict.

McKnight's attorney Roderick Carus called the prosecution's case weak and said he recommended that "authorities make more allowances for the frivolity of youth" in the future.

Ross McKnight told journalists outside the court that he had taken his high school exams behind bars and said he hoped the trial had not damaged his chance of joining the military.

"I would now like to put this behind me," he said.