Ben was with Tadaichi walking around as they were holding hands. The two then saw bloody footprints in the hallway they were in. They both follow it and it leads to Yuki who is dead in the chemistry room. 

Dead: Yuki Tesunochi 

Time of death: 6:00 pm

Cause of death: blood loss

Evidence: his throat is slit, a message is written on the side of his stomach which says"Sorry, I had to", there is bloody medium footprints that lead to the dorm area, a note that has some blood on it  is by Yuki's door. Then the footprints leads back to the chemistry as there is water on the ground.