Former Theranos board member, investor testifies against Elizabeth Holmes

Former Theranos board member and former Secretary of Defense James "Mad Dog" Mattis testified last week in the criminal trial of former Theranos CEO Elizabeth Holmes.

Former Theranos board member and former Secretary of Defense James "Mad Dog" Mattis testified last week in the criminal trial of former Theranos CEO Elizabeth Holmes.

"I was taken with the idea that with one drop of blood and with remote capability, you could basically test for a broad array of problems," Mattis told jurors from the witness stand during his initial examination from prosecutors.

When asked who was in charge in board meetings -- Holmes or her former romantic partner and Theranos Chief Operating Officer Ramesh "Sunny" Balwani -- Mattis did not hesitate when he said: "Ms. Holmes."

And when asked where he got his information regarding Theronos blood testing devices, he also named Holmes. "I had no other source of information on it," he told the court.