As for the professors I know there was McGonagle and Slughorn at least. There was also most likely professor Kettleburn who was the care of magical creatures prof before he retired.

---------- Post added 02-11-2013 at 07:04 PM ----------

Also I believe he started making the horcruxes around his 7th year so he's getting pretty evil at that point I would think though he always keeps that sugary sweet talk personality I believe.