I'm having a Murder Mystery for my sweet 16 i need more clues!?

For my Sweet Sixteen I'm having a Murder Mystery there are around 70 guests all high school students so I want the game to be hard enough so people do not think its lame but not to hard where no one will get it! All my suspects are like high school cliques a beauty queen, the football star, skater,drama girl, save the planet girl, cheerleader, the nerdy class clown, and the party girl . I need some more ideas for clues i have a love letter, necklace ECT. but any ideas you have would be greatly appreciated!!!