By Len Ramirez

SAN JOSE (KPIX) — For a third day, former Theranos CEO Elizabeth Holmes returned to the witness stand to testify in her own defense.

Holmes testified that she did not tell her business partners and investors that Theranos was making a major shift in company strategy — switching to commercial blood analyzers — to protect company trade secrets.

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“If you look at the past press she’s gotten, whenever she’s asked tough questions, she’ll use that, say we can’t talk about the technology it’s a trade secret, said Michele Hagan, a former prosecutor and legal analyst who is following the trial.

It was the most grueling day yet for Elizabeth Holmes with nearly 7 hours on the witness stand. Guided by her own attorney asking friendly questions, she addressed one of the prosecution’s strongest pieces of evidence: Holmes said she was the one who put a Pfizer company logo on some validation documents sent to Walgreens, even though Pfizer never validated Theranos.

Holmes said she did it because the two companies had worked on a previous project but said “I wish I hadn’t done that.”

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“It could be something that’s damaging, so it’s always good to get it out of your witness, to explain why that happened. For her to say she wished she’d done it different, maybe that will weigh with the jury. But the prosecution has already said, that it indicates deception,” Hagan said.

Holmes explained that Theranos stopped using its own small blood analyzing equipment shortly after the Walgreens launch. She said too many patient samples were coming in all at once for her finger stick machines to be practical. So Theranos switched to using big commercial analyzers which were modified to take small samples from patient’s veins, which was a new process.

Holmes said she never told Walgreens or her investors about that change to protect a Theranos invention, even though she did tell FDA regulators.

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Holmes also said she did not personally read or approve every word on her company website or marketing materials, but said she never approved any messaging that wasn’t true.