The once-heralded blood-testing startup Theranos is shutting down, according to a media report.

Theranos was unable to sell itself and is now looking to pay unsecured creditors its remaining cash of about $5 million in the upcoming months, according to an email The Wall Street Journal obtained that CEO David Taylor sent to shareholders.

Investors lost almost $1 billion in the company, The Journal reported. At one point, the business was valued at almost $10 billion, largely on the strength of its promise to provide blood testing through just a drop or two of blood. Former CEO Elizabeth Holmes' black turtleneck and lofty goals drew comparisons with Apple's Steve Jobs.

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But Theranos' blood-testing machines weren't reliable, and the company itself relied on other companies' devices to run blood tests.

The announcement of the closure comes nearly three months after Theranos founder Holmes and Chief Operating Officer Ramesh Balwani were charged with criminal fraud. Holmes, once considered a wunderkind in Silicon Valley, had pitched Theranos' technology as a cheaper way to run dozens of blood tests.

Prosecutors allege Holmes and Balwani deliberately misled investors, policymakers and the public about the accuracy of Theranos' blood-testing technologies going back to at least 2013.

Theranos laid off most of its staff earlier this year.