I bit down on a groan, my mind reeling. "Inside an empty office while inside an empty building."

"You got it."

"But there's no bullet hole in the window behind his desk."

"No. Which means the shooter was in the room with him."

"Or he was shot somewhere else and...deposited...here," I said, but the detective was already shaking his head. "No?"

"No. The shell casing was found across the room. One shot, and it happened in here."

"Then the only ...