Whistleblowers exposed the technology collapse at Theranos, the life science start-up at the center of a new HBO documentary.

In January, Tyler Shultz and Erika Cheung told their stories at a session hosted by Stanford University’s McCoy Family Center for Ethics in Society. They talked about how disorienting and frightening their experiences at the company were after they realized the touted blood testing system didn’t work.

Cheung said she doubted herself at first. She had a feeling “that there was something wrong going on here, but maybe there is something I’m not seeing. You’re surrounded by so many talented people… Everyone else was being very nonchalant about what was going on, just going through the motions and the grind of every day, knowing there were so many problems.”

More in this clip. A video of the entire session is available on YouTube. 

4/2 update: CNN reports that Cheung and Tyler have started an organization called Ethics in Entrepreneurship.