Gun Games by Faye Kellerman

Fifteen-year-old Gabriel Whitman is a very talented musician. Living with friends of his father, LAPD lieutenant detective Decker and his wife, Rina, Gabe has been home-schooled and will be going to Julliard or Harvard in the fall. In the meantime, he has few friends. When another teen is believed to have committed suicide, Decker is contacted by the mother who is certain her son did not kill himself. When another student commits suicide, Decker finds himself uncovering a group of privileged teens who like to play mean and nasty. Realizing that he does not really know Gabe, Decker tries to draw closer to him. A twisted tale of fear and loneliness, strange alliances, a good read.