A disgruntled ex-MI5 worker claimed to have undergone ninja-style training at its London headquarters in “swords and knives and stuff”, his partly-secret trial was told.
Juan Joseph, 43, had a lock knife in his pocket when he was arrested at an Ibis hotel for allegedly breaching the Official Secrets and National Security Acts in January 2025.
A search of his nearby home led to the discovery of a homemade card falsely identifying him as an MI5 officer, the Old Bailey has heard.
Joseph, a former IT contractor at the security service, was detained after he allegedly leaked sensitive information to a foreign power via emails and tried to arrange a meeting at an embassy in Latvia as he pursued a complaint against MI5.
In a police interview, Joseph maintained he was a “whistleblower” and was permitted to have the lock knife “as an officer” for “defence”, having bought it online.
He referred to taking self-defence training at MI5’s London headquarters, Thames House, with a ninjutsu instructor, which he said was “swords and knives and stuff”.
However, Joseph told police he only carried the knife as a deterrent and had not used it.
He also said he had a first dan black belt in taekwondo, as well as training in aikido, judo, and wrestling.
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When asked about his health, Joseph claimed to have suffered a heart condition after being “assaulted by a needle attack” in Thames House.
He told officers a swastika had been put up in the office and he was stabbed with a needle containing a substance that made him “very poorly”.
“I’ve now got a permanent problem with my heart which is hyperkinesia, which my heart doesn’t pump properly,” he said.
Joseph insisted he had not done anything wrong and was the victim of racial abuse attacks while working at MI5, according to interview transcripts read out in court.
Commenting on the allegations made against him, he said: “I don’t believe there is anything there that could be damaging to the United Kingdom, otherwise I wouldn’t do it, you know?
“I can only reiterate, there’s no malice there, there’s no wilful intent for me to hurt anybody.”
He added: “I’m not a threat to the country, I would never do that you know. It’s quite hurtful that people are saying things like that about me and that’s the God’s honest truth.”
Joseph had the highest vetting clearance during his 11 years at the security service, working as a systems engineer, a security IT management engineer, and a senior support engineer.
His contract was terminated in October 2020 after he was taken to hospital displaying what colleagues described as “mental fragility”, “extreme anxiety” and “paranoia”.
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Joseph made unfounded complaints about “racialist comments” and violent offences, including rape, child abuse, and torture, jurors have heard.
The alleged offending began in 2024 after a bid to bring a private prosecution for an alleged assault in 2019 was rejected.
The defendant, from Sutton, south London, has denied four charges under the Official Secrets Act and National Security Act.
He has also denied having an article with a blade or point when he was arrested at the hotel in Sutton.
The Old Bailey trial, which is being partly heard in the absence of the public and press, continues.
