When counter-terrorist detectives raided Mohammed Humza’s house in Watford, on the outskirts of London, they found a MacBook computer which he had used to log onto the Darkweb, a court heard on Thursday, 8 October.
Prosecutor Benjamin Holt said Humza, 29, had used the username mh.nn243 to log into the AlphaBay marketplace and agree deals to buy F1 fragmentation grenades and Semtex explosives.
He was arrested in November 2016 when it turned out the person mh.nn243 was trying to buy them from was actually an undercover FBI agent.
Humza, who not in court, has denied attempting to possess explosive substances for unlawful purposes between July and September 2016.
Mr Holt pointed out the username contained the initials of Humza and his wife, Nazir Naz.
But Humza, who answered no comment during police interviews, claims he was not the only person to have access to the mh.nn243 username.
On Thursday, 8 October, Anders Ho, a National Crime Agency officer gave evidence at the trial at the Old Bailey.
Mr Ho, who works for the NCA’s Darkweb Intelligence and Exploitation Unit, said he had carried out several test purchases on AlphaBay before it was closed down by the US authorities in 2017.
He explained that the only way two people could user the same AlphaBay username was if they both knew the username, the password and the PGP (Pretty Good Privacy) encryption key.
Francis McGrath, counsel for Humza, asked him: “Was it possible for people t manually delete a conversation on their account?”
Mr Ho replied: “It was very similar to eBay, very similar in design at the time. I would infer that it woul be possible to do so but I can’t say so definitively.”
Mr Holt then asked him if it was not the case that while an order was progressing there was no way of deleting that order on AlphaBay.
“Until the point when all parties were happy and it’s been finalised, which is a technical term, then no, the order would have to be displayed,” replied Mr Ho.
The jury has been told that at one point mh.nn243 asked a seller on AlphaBay: "What's the best price you can do for 2 grenades with postage to the UK?"
He was quoted $115 (£90) each for four grenades and said they would need to be delivered to "Watford" in "Hertfordshire."
The deal was never completed but mh.nn243 later agreed to buy two grenades and transferred Bitcoin funds into an escrow account.
Later the FBI agent who was posing as the seller said he had run out of grenades and refunded the cryptocurrency.
At that point mh.nn243 discussed buying Semtex and a fuse detonator.
Detective Constable Ruth Hayter told the jury detectives raided Humza’s home in Watford on 11 November 2016 and discovered a MacBook computer which had been used to access AlphaBay using a Tor browser.
She confirmed that among the internet searches which had been made on the computer was one for “shipping a gun to the UAE [United Arab Emirates].”
Det. Con. Hayter said there was also evidence suggesting Humza had used another Darkweb marketplace, Silk Road, and had shown interest in a New York driver’s licence and an electronic hotel key bypass gadget.
The jury is expected to retire and consider its verdict on Friday, 9 October