Detective Allegory

She is a time travelling detective who tries to completely prevent famous murders from even happening, but she's not conventionally intelligent. She tends to make problems worse before better unintentionally, and the like. She's kind of like some tourist for different time periods who gets themselves into trouble trying to be helpful, but does her best to make things right in the end because she has a heart of gold. It is very common for her to go back to the same event over and over to fix her mistakes.