A teenager who stockpiled explosives but denied planning a Columbine-style attack has been detained under the Mental Health Act indefinitely.
Michael Piggin, 18, admitted stashing parts of pipe and petrol bombs in his bedroom at home in Loughborough, Leicestershire.
A jury at his Old Bailey retrial failed to reach a verdict on terrorism charges. He will not face further prosecution.
The judge said he needed treatment.
Recorder of London, Brian Barker QC, told Piggin he was detaining him “under the Mental Health Act, which will provide you with appropriate treatment for as long as is deemed necessary”.
The judge added that the potential danger to the public was “uppermost” in his mind.
“Cases of this type are fortunately rare but of great concern to the public and normally would attract long sentences,” he said.
“Given your personal condition, this is not a case of a determinate sentence. It is clear from reports that you need treatment.”
Piggin was diagnosed with Asperger’s syndrome, a form of autism, after his arrest in February last year.
Police found a hoard of weapons and explosive devices as well as a Nazi flag on the wall of his bedroom and a notebook with a list of potential targets.
He admitted three explosive offensives and possession of a knife but denied two more serious terrorism-related charges.
During the trials, jurors were show footage of Piggin throwing petrol bombs behind a leisure centre and writing racist graffiti on a wall.
Throughout the case, Piggin denied any real plans for attacks and said it had all “just been in his head”.
He said he “didn’t have a problem with Muslims in general” and described racist comments made on videos as “banter”.