Keeping your daughter safe sounds like a difficult task and one that may require professional intervention.
Increase the monitoring of her whereabouts so that you can accurately report to the police when she leaves your home without permission. Ultimately, you are responsible for her and her safety no matter where she is. If you don't know where she is, then reporting that to the police is the responsible thing to do.
The other suggestion we have is to get your daughter into counseling. There is something going on with her, and unless she can be redirected to follow the right path, she will only get herself into greater trouble. Sometimes her school counselor can be helpful, and there are also numerous counselors available in nearly all communities. Many times these counselors charge according to the client's ability to pay.
If this behavior continues to the point where you feel she requires a higher level of care than you can provide in your home and family, a residential treatment program may be appropriate. But the program leaders will want to know that you have already tried other avenues. If you would like help in accessing services, counselors or out-of-home placements, let us know what city and state you are in and we can provide ​referrals.