At a university, when medics are called the police are going to be called - particularly when possible alcohol poisoning is involved. It is a HUGE liability issue for the university. CLEARLY she made statements or took actions that indicated to a number of people that she was a danger to herself or others.
And, let me tell you from personal experience, the line you just wrote, "She wouldn't kill herself ..." is one of those things that one hears often from the mouths of those who have been left behind. Not all those who are suicidal leave a clear trail. While you may very well be right, if she makes statements to all those professionals - or takes actions - indicating otherwise, they are legally bound to take action.
When your friend is released, she can consult attorneys to see if there is any legal action to be had. Until then, as I mentioned, you can be there to support her.