YA, murder mystery?? hardback with red&blueish cover

Got the book for free at school in May 2015. Its YA and about girl who recently moved into a house and was starting a new school. Setting is somewhere in California, possibly hollywood. the house is big and where i can remember most of the book taking place. there is a pool in the back and one day the girl decided to go in and when she did there was a figure, she freaked out and got out and looked at the pool but couldn't see anything. happens multiple times where she goes in and sees/feels something in there with her. pretty sure she finds out that someone was unalived in the house and thats who was in the pool with her. the paper part of the cover is a picture of a girl with her back facing the 'camera' while in the pool, the letters are in white above her, behind the letters/what shes looking at is just mountains. its hard cover and without the paper cover its either a red spine with a light blueish cover or a blueish spine and red cover

>1 cinthiap: Could it be Famous Last Words? The cover doesn't match though, but they don't always.