if you've made it down then you're close, if you go stight you'll find a druids diary wich explains how to make perception potions in case you need them (i guess you do) [eye + vial + boosting ingreedient] the corpse itself is behind a hidden wall on the road to the right.
Then it seams we are stuck on the exact same spot, its worse that the book about trial logs hints to the midle of the library aka the candles, but I can't figure it out
