>>This is the inciting incident for her to look for the murderer of the current victim,
But why wouldn't she investigate the current murder anyway even if none of the clues matched? Isn't that her job -- to solve murders?
If she's the sole homicide detective in the department, then it's her job to investigate any murder that happens -- she has no choice. And if she's one of several homicide detectives, her supervisor would assign the case -- that's SOP-- so again she would have no choice.
However, if she asks for the case to be re-assigned to her after realizing the coincidence of circumstances, then it might qualify as the inciting incident. And the coincidence would add psychological overtones as she has to revisit the traumatic memories of her mother's murder. Especially if she witnessed her mother's murder. Did she witness her mother's murder?