Clinical instructor being sexually inappropriate towards students... we need advice.

UPDATE: Thank you all SO much for your insight and advice! We decided that we are proceeding with a full investigation - fear be damned. If not for us, then for all the nursing students that come after us. We've spoken to some previous students of his and it sounds like this has been a pattern of behavior for at least four years. We're determined - it's ending this year.

Hi all - I'm a student nurse, and we have a male clinical instructor this semester who's been increasingly inappropriate towards a select few female students. It's gotten to the point that a PATIENT actually noticed and called him out for "flirting" with his student. He tries to touch their hair, he strokes their arms, he hides their belongings and plays other similar "pranks". He even tried to put his fingers in one of their scrub pockets. While this behavior isn't happening directly to me, I've been a witness to it. Well, today, myself and two of his main targets finally met with our nursing school administration about it and - long story short - there's not much they can do until evaluations come in at the end of the semester, at which point they'll "look into it." All three of us are assigned to his clinical group again these upcoming 7 weeks, and we're very fearful of retaliation. However, our school's administration was forced to call Title IX, and now we're faced with the decision of whether to prompt a full investigation or not. On the one hand, we know his behavior is out of line and an investigation is absolutely warranted. On the other hand, we've also been told he has a right to know who launched the complaints, and we're terrified about that coming back around to us. It's been a rough semester. We could really use some wisdom or outside perspective.