The fallen servants and the guards on the floor and the pitiful condition of Violet's office allowed him to make a shallow guess as to what had transpired in the Windsor family mansion but he needed concrete information to develop his own judgment.
Since Clara didn't seem like she was in a state to narrate the events to him clearly. He just held her close to himself in order to keep her from doing something stupid and looked towards the only person who could be of help to him; Luke, the person he had met before in the streets while chasing after Clara.
"Luke…right?" asked Zach so as to build rapport with the only witness available to him. Although, they had met before, they were not very close to each other. Therefore, it was only right to start with the basics.