>> robyn garfield: yes. ultiple times that day. >> britta garfield: we went on a walk and she just fell on her face. it was very abnormal. she never does that. and then a second time, she completely lost her balance and just fell to the side. >> pelley: in 2018, then- secretary of state mike pompeo confirmed the case of catherine werner. upenn found her brain injuries matched the cuba victims. >> mike pompeo: we had an incident in guangzhou that the medical indications are very similar and entirely consistent with the medical indications that have taken place to americans working in cuba. >> pelley: for reasons that are unclear, the state department was raising doubt about the other 14 china cases. in 2018, the department's medical office sent mark lenzi a note that said, "we have reached the decision that your symptoms and findings do not correlate with the havana cohort." >> lenzi: they tried to deny it. they tried to cover it up. they tried to minimize it. >> pelley: why would the state department minimize