The Night Shift

The Grandview Hotel is quiet at night. Too quiet, some guests say. The hallways are long. The lights hum. The walls are thin.

One night, a woman checked into room 304. She hung the “do not disturb” sign on her door. Nobody ever saw her alive again.

The next morning, a maid found her body. She had been killed late at night.

The police arrived fast. Three employees had worked that night. The police questioned all three.

The security guard said:

“I was watching the entrance all night. Nobody came in. Nobody went out.”

The receptionist said:

“I was at the front desk. I only left once to use the bathroom.”

The cleaner said:

“I was vacuuming the hallway.”

The police arrested one of them right away.

Who did it? And how did the police know?