u/Awkward-Poet-5113

I recently read a book but can't recall its name as well as author's name:
the story started with a girl running from someone (probably murderer) in the woods to get to the highway but ended up being caught...the flashback cuts of and she was sitting right before the private investigator who is trying to solve a murder case (probably) by asking her what she found in the deck of the boat and suddenly another flashback starts where she was in the boat and she found a dead body of a guy and describes it as it was so beautiful.

It was one of the instant best sellers.

Can you help me finding the book?