"I had no choice but to create a locked room". Okay, BUT WHY THOUGH??
Seems like after killing the first victim the woman had three options:
1-Just split. Nobody would know it was her.
2-Make it seem like the victim tripped and accidentally hit her head, then use her locked room trick. Nobody would know it was her.
3-Make it seem like some tall serial killer killed her and that for some reason his MO includes locking rooms with a trick.
Why would anyone go with the third option? But okay, this is salvageable, since the trick is already posted online anyone could have used it. Nobody would know it was her... Oh shit, nevermind, she killed more people after that, the evidence piled up and she was found out.