SAN JOSE — Elizabeth Holmes’s testimony in her own defense concluded its third day Tuesday with a key message: She was acting in good faith.

She said she asked the right questions and presented the right image to potential partners — while trusting her employees to properly convey things to her. She believed the information she was providing to her prospective business partners. And she denied she pressured any employees to validate blood tests if they weren’t comfortable doing so.

She admitted that Theranos was running blood tests on modified third-party machines without telling its business partners and that she added the logos of two pharmaceutical companies to studies Theranos sent to investors. But Holmes presented her decisions as reasonable and within the normal course of business.

“This was an invention that we understood from our counsel we had to protect as a trade secret,” she said of the modified third-party machines.

The prosecution will have the opportunity to tear the picture presented by her defense apart as soon as next week, when they cross examine her. But her hours of testimony so far painted a picture of a thoughtful and earnest CEO who was trying to do her best and made understandable mistakes.

Holmes gained widespread media attention roughly a decade ago as a rare young female start-up founder who was defying the odds in biotech. She claimed her technology was capable of running a multitude of tests on mini lab machines with just a few drops of blood. Her signature look included black turtlenecks in the style of Steve Jobs, she spoke in a low voice, and she wowed audiences with presentations on the company’s ambitions. She founded the company as a college student at Stanford University, then dropped out to propel the company to raise roughly $900 million from investors in a storied Silicon Valley office building employing hundreds of people.

But that all came crashing down following a 2015 Wall Street Journal investigation into the company’s technology that showed it wasn’t performing as advertised. Theranos crumbled in 2018 after years of media and regulatory scrutiny into its portable blood-testing device, which has also been the subject of a book, a documentary and multiple podcasts.

Holmes faces 11 charges of wire fraud and conspiracy to commit wire fraud and has pleaded not guilty.

The prosecution rested its case last week after calling 29 witnesses during more than two months of trial. Former employees, business partners and investors expressed their disappointment and concern with Theranos when they learned of inconsistent blood-test results and the start-up’s reliance on third-party lab machines.

Holmes was largely absent from public view after the company collapsed until her trial began this year — she now wears her blond hair down in loose curls and has ditched her black turtlenecks for dresses and skirts in grays, blues and greens.

During her testimony, she listened intently to her lawyer, rarely taking her eyes from him, except to review documents and emails in the large binder in front of her.

Her answers to his questions were often brief — “I did” or “Yes” — as he walked her through various emails and presentations that charted Theranos’s route from a young technology company courting pharmaceutical partners to a more mature firm that had its own manufacturing center and partnership with a major retail pharmacy chain.

Holmes maintained a calm demeanor and answered his questions in a pleasant and measured manner. She smiled occasionally and projected confidence.

In her signature deep voice, she explained at a high level how the company’s technology processed blood samples and what developments Theranos worked on to be able to run more tests at a time.

Holmes’s testimony largely focused on what she knew about Theranos’s relationships with pharmaceutical companies and retail chains, including Walgreens. On the stand Tuesday, she confirmed that she was the one who added the logos of two pharmaceutical companies to validation studies that were sent to Walgreens while they were deciding whether to work with Theranos.

Those two studies have been key to the government’s case against Holmes — prosecutors have alleged for the first two months of the federal trial that Holmes knew the limits of the company’s technology and that Theranos overplayed what it said were approvals with two large pharmaceutical companies by affixing the logos to the reports.

The reports were the results of studies Theranos conducted with the two pharma companies in part to evaluate how well Theranos’s technology worked compared to traditional lab methods. But witnesses from both Pfizer and Schering-Plough testified early in the trial that they were unimpressed with Theranos’s technology and did not pursue further partnerships with the start-up. They said they did not approve the final reports that Theranos sent to Walgreens and to investors.

Lead defense attorney Kevin Downey asked Holmes on Tuesday if she intended to make it seem like the reports were prepared by Pfizer and Schering-Plough when adding the company’s logos.

That wasn’t her intention, she said, but she heard the testimony that previous witnesses felt it was misleading.

“I wish I’d done it differently,” she said.

Holmes said she sent the reports because she wanted to show Walgreens and others that Theranos’s technology worked well compared with traditional lab methods.

Several times, Holmes noted that other Theranos employees were the lead on projects or said that she was acting on information she received from her employees. This has been part of her defense strategy — to note that other, well-qualified workers at the company were giving her information that she believed.

She also hit on a key allegation that has come up often during the trial — that Theranos was using third-party machines to run most of its blood tests while telling investors and business partners it was using its own devices.

Theranos was relying on third-party machines that the company had modified to work with its small blood samples, Holmes said, but it didn’t talk about it to nearly anyone outside the company because it was protecting its intellectual property.

“This was an invention that we understood from our counsel we had to protect as a trade secret,” she said.

Theranos was relying on the modified machines because its own devices couldn’t handle the amount of blood samples the start-up expected to process when it decided to operate a central lab in its partnership with Walgreens, Holmes said. Theranos’s devices were designed to work on one sample at a time, a system the company planned to use when it was initially planned to put devices inside Walgreens stores.

The plan shifted to instead collect samples at Walgreens locations and process them at Theranos’s lab off-site, she said.

Prosecutors and previous witnesses have alleged that Theranos relied on the third-party machines because its own devices weren’t working well enough and couldn’t handle the work the company’s partnerships brought in.

In court filings before the trial began, Holmes’s defense lawyers suggested the entrepreneur may argue that abuse by her ex-boyfriend, who was the company’s president, rendered her incapable of making her own decisions. But so far, the allegations have not surfaced during the trial.

Her former partner, Sunny Balwani, faces a trial next year on the same charges. He has pleaded not guilty and denied the abuse that was alleged in court filings.

Balwani’s name came up several times during the trial on Tuesday, especially when Holmes testified that he was in charge of preparing the financial projection documents that were provided to the board of directors.

correction

Theranos raised roughly $900 million from investors. An earlier version of this article incorrectly said that was the company’s peak valuation. This article has been corrected.