Disgraced biotech star Elizabeth Holmes began serving her 11-year sentence for defrauding investors in a Texas prison on Tuesday.
The 39-year-old was seen arriving at the minimum-security federal prison for women inmates in Bryan, Texas near Houston.
She was ordered to begin serving prison time at the facility on Tuesday after a court denied her latest request to remain free while appealing her fraud conviction.
"We can confirm Elizabeth Holmes has arrived at the Federal Prison Camp Bryan... and is in the custody of the Federal Bureau of Prisons," the authority said in a brief statement.
Holmes became a star of Silicon Valley when she said her start-up was perfecting an easy-to-use test kit that could carry out a wide range of medical diagnostics with just a few drops of blood.
As founder of Theranos, Holmes became a tech celebrity, winning investments from top politicians and some of the world's richest people, including media baron Rupert Murdoch, Oracle founder Larry Ellison and pharmacy chain Walgreens.
Theranos also became famous for the notable figures sitting on its board of directors, including former top US government officials Henry Kissinger, George Shultz and Jim Mattis.
But the fortune of the Stanford University dropout flamed out after a Wall Street Journal investigation into the validity of the tests.
Holmes had a child shortly before her trial and has had a second since her conviction.
In addition to her prison sentence, she and former top Theranos executive Ramesh "Sunny" Balwani have been ordered to pay US$452 million to the bilked investors.
Balwani was sentenced to nearly 13 years and is currently serving his time at a federal prison in California. (AFP)