Elizabeth Holmes, founder and former chief executive officer of Theranos Inc, exits federal court in San Jose, California, US, on Monday, April 22, 2019. Photo:VCG

Convicted Theranos founder Elizabeth Holmes asked for a new trial, saying a star prosecution witness showed up at her home saying he felt he had "done something wrong."

Holmes is scheduled to be sentenced in October after a jury early in 2022 found her guilty of defrauding investors in her blood-testing startup Theranos.

Holmes is a rare example of a tech exec being brought to book over a company flaming out, in a sector littered with the carcasses of money-losing businesses that once promised untold riches.

Her case shone a spotlight on the blurred line between the hustle that characterizes the industry and outright criminal dishonesty.

But attorneys for Holmes said that former Theranos lab manager Adam Rosendorff, who was part of the prosecution's case, arrived unannounced at her California home in August looking disheveled and saying he needed to speak with her.

"He said he feels guilty, it seemed like he was hurting," Holmes's partner, William Evans said of Dr Rosendorff.

"He said when he was called as a witness he tried to answer the questions honestly but that the prosecutors tried to make everybody look bad [in the company]."

Evans said that he turned Rosendorff away from the home he shares with Holmes and their young son, telling Rosendorff that Holmes could not speak with him.

Holmes had vowed to revolutionize health diagnostics with self-service machines that could run an array of tests on just a few drops of blood, a vision that drew high-profile backers and made her a billionaire on paper by the age of 30.

She was hailed as the next tech visionary on magazine covers and collected mountains of investors' cash, but it all collapsed after Wall Street Journal reports revealed the machines did not work as promised.

Jurors found her guilty of four counts of tricking investors.

The 38-year-old now faces the possibility of decades behind bars.

AFP