Fiction mystery: professor's daughter's private school teacher found dead

Can't think of the title, read it in the 1-2 years ago:

Very smart high school girl protagonist, attends private school and falls in with the very-smart-mean-kid-in-crowd, who are taken under the wing of one free-spirited teacher who is soon found dead in the woods during a group camping weekend. Turns out teacher and girl's professor-father are part of some extremist group.

Sound familiar? Any help would be appreciated. --Mae

Maybe Special Topics in Calamity Physics by Marisha Pessl?