I suspect someone was hired into a senior position at Tufts Medical Center using fraudulent credentials. Who should I notify?

I would have to say contact their Human Resource Department, but if you don't have any proof they have nothing to investigate with. I wish you luck...

Go to their hr department.

As sad as it may seem it may not matter in some departments they don't look a credentialing they just look at the relationship between the person that's usually has the false credentials in people in positions of power it's sad but true I had the same problem. Good luck. I went to their HR person because I was actually being harassed by the person for having more credentials than him and they supported him. Again good luck