. >> reporter: doug mechie joined theranos in 2012.ob was to adapt blood tests for the edison. tests which holmes told investors were ready to use on patients. >> but liz beth holmes told walgreen's in 2010 it developed a device capable of running any blood tests from a few drops ricked from a finger in real time and half the cost of traditional labs, was that true? >> no. >> do you think she was lying to walgreen's, i do. >> are you a clinical lab specialist? >> no. >> erika chung out of berkeley with a degree in molecular and cell biology when sunny went to work, she was 22. even the novice lab tech suspected something was very wrong when she saw faulty test results sent to wal green's patients. >> when did you thing i probably shouldn't be doing this? >> pretty, pretty soon in the process. especially when weep started to pick up more patients samples. >> when the samples were retested, she says, there were often contradictory results. >> reporter: did you alert the patient? >> no. we didn't let them know, hey, we reran your patient