My friend was raped..........?

okay so here's the story. she was 15, the guy was 18. she told him she was scared & wasnt ready, blah blah blah, but he kept pushing. after it happened, we called the cops. they took his sheets & her clothes for evidence. its been about 4 weeks & still no word from the cops. we said we wanted to press charges. but they arents doing anything. & the dudes gonna be leaving soon to go off to college. we live in california, so im not sure if the state laws have some factor in why nothings happening? all i want to know, is what we should do to get justice. to speed up the process with the cops, because at this point, it looks like they arent going to do anything about it. help?