Jim Mattis testifies that Elizabeth Holmes misled him about Theranos

Former Defense Secretary Jim Mattis testified on Wednesday during Theranos founder Elizabeth Holmes' criminal trial, saying that he was misled to believe the company had developed a technology that could scan health issues with drops of blood, AP reports.

State of play: Prosecutors presented Mattis' testimony to support their allegations that Holmes lied to investors about having a business relationship with the Pentagon, per the Wall Street Journal.

• Mattis joined the Theranos board in 2013 and invested $85,000 of his own money into the company, shortly after retiring from the military. He said that he believed that the technology could help save the lives of troops on the battlefield.

What they're saying: "There just came a point where I didn’t know what to believe about Theranos anymore," Mattis said, per the Journal.

• Mattis said that after Holmes showed him the technology, he "did not want to miss an opportunity."

Catch up quick: A series of stories from the Journal revealed that Theranos' technology did not work as advertised, which led several investors to sue the company.

• Theranos is considered "the biggest fraud to have ever come out of Silicon Valley," Axios' Kia Kokalitcheva writes.

What to watch: Other Theranos board members include former Cabinet members and CEOs, AP notes. Some are expected to testify during the trial, which is scheduled to continue until December.