SAN JOSE (CBS SF/CNN) -- Former lab director Adam Rosendorff was scheduled to return to the stand Tuesday at the federal fraud trial of Theranos founder Elizabeth Holmes after leaving jurors with a lot to consider over a long weekend break.
During his testimony Friday, he described a sudden change in Holmes characteristic confident body language when he told her the revolutionary blood testing procedure her medical startup was set to launch wasn't working.
Rosendorff told jurors he addressed his concerns in an email to Holmes and had a conversation with her in her office, where she had "papers stuck on to the window with a number on it, which indicated the number of days until launch."
"I told her that the potassium was unreliable, the sodium was unreliable, the glucose was unreliable, [and] explained why," Rosendorff testified.
"She was very nervous. She was not her usual composed self. She was trembling a bit, her knee was tapping, her voice was breaking up. She was clearly upset," he continued.
He said she responded that they could use conventional FDA-approved devices rather than Theranos' devices as needed.
Rosendorff, who joined Theranos in April 2013 after applying for a lab director job on LinkedIn, was questioned for roughly five hours by assistant US Attorney John Bostic.
READ MORE: Complete Coverage of Theranos Trial
He left his lab director job at the University of Pittsburgh Children's Hospital to work at Theranos, which he said he believed "was going to be the next Apple."
But he departed in November 2014, even as the company's profile was rising, after growing uncomfortable with its apparent priorities.
"I felt pressured to vouch for tests that I did not have confidence in. I came to believe that the company believed more about PR and fundraising than about patient care," he began his testimony. "The platform was not allowing me to function effectively as a lab director."
In his testimony, Rosendorff called the events leading up to the commercial launch of Theranos' testing with Walgreens in September 2013 "extremely rushed and hurried."
Despite being lab director, Rosendorff was also notably left off some emails that discussed concerning Theranos test results.
He testified that he felt he "absolutely" should have been included on them; Holmes and Former chief operating officer Ramesh "Sunny" Balwani, however, were looped in on the emails. Echoing testimonies from earlier former Theranos employees, Rosendorff also said he was troubled by the lack of protocol for deleting certain data points to pass quality control as well as the high rates of failure when it came to quality control of tests.
Balwani and Holmes are both facing a dozen counts of federal fraud and conspiracy charges over allegations they knowingly misled investors, patients and doctors about the capabilities of Theranos' proprietary technology. Balwani and Holmes have both pleaded not guilty and face up to 20 years in prison. They're being tried separately, with Balwani's trial set to begin early next year.
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