Dying Gwang shik was on her hands and she didn't even try to touch him quickly while he was still breathing... uhm, thought you learned from your previous mistake? What a frustrating FL.
her character has a lot of flaws and this is one of them... the classic way how to hate the main characters. I don't know why the writer wrote her this way.
I love all the theories given by others. It is either the cop (Ok-hui's brother) or the shaman. One person commented before that it could be the cop, a self-righteous type of person, but this led me to the question, if he wants to punish the baddoers, why frame the old doctor? Because he was caught in the act? It could be. On the other hand, the shaman revealed that he has been half asleep most of the time which caused him a lot of memory loss even the most recent events in his life. Theories about him having multiple personalities could also be true.
she is a vet, not a human doctor, so that explains not noticing parkinsons, especially if they weren't close.…
This may sound dumb but she probably killed her (while closing her eyes) before she ran for help. That way she can give an excuse why she didn't ask for help from the other people she first encountered.