They didn't suspect she was Felina until they had seen the account open on her phone. Why would they torture her if, until that point, they already had the unrelated plan of retribution?
If I were in that line of business, I would assume that everyone has valuable information and would take steps to capture that information before it is destroyed. Other valuable information - especially that a physician might carry - might include contacts to other physicians for extortion or medical records on politicians or other adversaries.
I think many intelligence agencies have a similar outlook.