Theranos trial: Elizabeth Holmes took US general's blood

James Mattis served as Defense Secretary under Donald Trump

A former US defence secretary has described how he lost faith in the technology company that took his blood as part of testimony in the case against disgraced Theranos founder, Elizabeth Holmes.

General James Mattis, who was on the company's board, said he was initially "amazed" by Ms Holmes' blood tests.

But by 2016 he "didn't know" what to believe after she was accused of fraud.

Ms Holmes, 37, denies the charges that she deceived patients and investors.

She could face 20 years in jail if found guilty.

Once dubbed the "next Steve Jobs", the former entrepreneur rose to fame in 2013 thanks to technology she claimed could test for multiple diseases using just a few drops of blood from a finger prick.

But by 2015 it emerged the tests did not work and the billionaire inventor fell from grace.

Gen Mattis, who served under Donald Trump, was one of a number of political grandees to sit on the Theranos board - in his case between 2013 and 2016.

On Wednesday, he told the court in San Jose he had been "rather taken" with Ms Holmes' technology. She even drew his blood backstage after an event in San Francisco in 2011 to show how easy the tests were to use.

"This was something so new, I was frankly amazed at what was possible based on what Miss Holmes said," he commented.

He added that the entrepreneur - who also convinced high profile investors such as Rupert Murdoch to back her - was "sharp, articulate, committed".

The four-star decorated general invested $85,000 of his own money in the business.

When in 2015 the Wall Street Journal reported that Theranos's tests were flawed, Gen Mattis initially thought an "aggressive reporter" was misrepresenting the facts.

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The newspaper also claimed Theranos was doing most of its testing on commercially available machines made by other manufacturers.

"There came a point where I didn't know what to believe about Theranos anymore," he said, adding that he soon stopped attending board meetings.

Once considered a visionary, Ms Holmes was banned from running a blood testing company for two years in 2016, and saw her company dissolved in 2018.

Prosecutors say Ms Holmes and her ex-boyfriend and partner - Ramesh Balwani - turned to fraud in 2009 after big pharmaceutical firms declined to back Theranos and they ran out of cash.

They allegedly lied about the tests and exaggerated the firm's performance to secure $700m of investment.

However, Ms Holmes lawyers say she did not intend to defraud, but instead "naively underestimated" the challenges her business faced.

Ms Holmes has also alleged Mr Balwani abused her emotionally and psychologically for years, impairing her mental state. Mr Balwani has denied the allegations.