Responses
It was revealed that Issac was the killer that the main cast was trying to hunt down... Which was just god awful writing since they don't even look alike and the timing of the murders don't add up.
At the end FL "killed" him and there was no more murders for a short time but it's revealed Issac is actually still alive and the story leaves at a clifthanger...

I dropped this before and forgot why I'm planning to reread it, can someone spoil me the ending I've seen the comments and y'all were disappointed