A bank worker from Maidenhead has been charged in connection with a scam to defraud Lloyds Banking Group out of £2m.
Neil Bautista, 23, of Northumbria Road, along with two other men has denied his involvement in the conspiracy.
It is claimed stolen log-in details were used to defraud Halifax bank branches in Slough, Newbury and Camden.
Bank clerks Tai Hulbert-Thomas, 27, from Carlton Road in Oxford and 30-year-old Mawli Thurairajah from Moelyn Mews in Harrow were also charged in connection with fraud said to have taken place between July and September 2012.
The three are standing trial at the Old Bailey.
A fourth man, 22-year-old Joe Mariathas of Stonewall in East Ham, has admitted fraud by abuse of position by installing a device on a computer and to another charge of conspiracy to defraud.
Lloyds Banking Group, which is merged with Halifax, first became aware of the scam in August 2012 after the branch manager of a Halifax branch in Slough discovered a suspicious transaction of £50,000 had been made into a customer's account.
The court was told a subsequent investigation found 13 accounts had received fraudulent credits totalling £605,000 all between 5.59am and 7.15am on the same day.
The probe found that one of the computers had been tampered with, allowing it to be remotely accessed through the internet.
CCTV footage was also found showing Bautista leading a man into the room at the branch where the computer was located shortly before the bug was installed.
James Thacker, prosecuting, told the jury: "Bautista was in the room with this man at the time when the device was placed on the computer."
Bautista later claimed he had been approached by a gang who threatened to kill his mother if he did not cooperate.
The prosecution has claimed the amount intended to be obtained from all three branches was £2m but the loss to the bank was just over £440,000.
Bautista denies conspiracy to defraud and fraud by abuse of position.
Hulbert-Thomas and Thurairajah deny the same charges.
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