Mr Chamberlain and Mr Lynch were both charged in 2018 and have pleaded not guilty. Both have lodged legal attempts to throw out the cases.

Darktrace counts Mr Lynch as a founding investor and employed Mr Chamberlain as its chief operating officer until he was put on leave and subsequently left. Neither have any active role at the company.

Ms Gustafsson reported directly to Mr Chamberlain in Autonomy’s finance department when the company was sold to HP and gave evidence in a UK civil trial between HP and Mr Lynch.

Filings from Mr Chamberlain describe her as a “critical witness” who could support his defence.

The legal documents state: “She is also copied on emails that the Government may use to suggest were indicative of Mr Chamberlain’s criminal intent and, based on her testimony in the UK civil case, Mr Chamberlain believes she will provide testimony that is exculpatory as to him.”

Mr Chamberlain has applied for a court order to request Ms Gustafsson and Ms Harris deliver out-of-court testimony in the UK.

If they do not volunteer, the court could request that UK authorities compel testimony. The US government has made a similar request regarding Matthew Stephan, another former Autonomy employee.

A Darktrace spokesman said: “No decision will be made on next steps until the court has ruled on these motions. As a reminder, no current executives at Darktrace have been indicted or charged in these legal proceedings.”