Dr. Evans

The room was suddenly warm, so warm, and the mask was suffocating me. I wanted to pull it off so I could breathe. I must have made some movement, because the doctor grabbed my wrist.
"Don't take anything off. I'm risking their lives with every new person that comes in here." He let go of my wrist. "Make the risk worth it. Tell me what did this."

(Obsidian Butterfly, page 48, paragraph 2)

* Dr. Evans isn't given a first name in the book.

* He comes highly recommended by Ben, which is something that Anita trusts. When she first meets him, he is in scrubs, so he is not described very much.

* His wife, Leonora, is a witch.

* He tried to test the "survivors" of the attacks for higher brainwave function, since Anita thought zombies would not have them, but they did.

* When they finally attacked, Evans' arm/wrist was bleeding profusely.