Your friend needs to consult ASAP with an experienced criminal lawyer. Not enough facts are presented here to make any recommendation but the obvious one, hire a lawyer and get advice after explaining all the facts concerning the situation.
Your friend is going to have to hire an attorney to guide them through this process. Use the Avvo Find-a-Lawyer feature to identify someone in your area. I also suggest you re-post your question in the criminal defense area of Avvo as someone local might be online
Personal injury cases only; I'm good at it; you be the Judge! All information provided is for informational and educational purposes only. No attorney client relationship has been formed or should be inferred. Please speak with a local and qualified attorney. I truly wish you and those close to you all the best. Jeff
Your friend would want to retain a criminal lawyer who can orchestrate the turning her in process easier.