I would be worried but not extremely worried. I would actually not be asking advice from a forum like this or from the internet at all, you should be talking to an attorney and seeing what he/she says. Good reputable attorney's often give 1 hour free consultations. Or do you have a friend who is an attorney who could advise you.
I would continue on with your journey into Nursing or phsycianhood and follow what your attorney tells you to. The internet is a minefield of bad advice and please don't step into it without getting an attorney involved.
did the investigator tell you why it's taken 2 years for them to get into this? This sounds like someone from your past is throwing stones and trying to see what will hit. did you have someone you pissed off way back at your old school that might have a old axe to grind??? Be honest with the investigator but only after you speak with the attorney.
Do you see the underlying theme of my advice - don't do anything until you have talked to your attorney. I wish you the best.