The Glass Rhythm of Death

The main pipe supplying the mansion froze due to the snowstorm. The recorded water flow rate in all taps and bathrooms was exactly (zero liters) from 9:30 PM to 11:00 PM.

The projector was not turned on all day because its lens burned out yesterday. The room's recorded electrical consumption between 10:00 PM and 11:00 PM was zero watts.

The four glass walls of the court are covered with a thick, continuous layer of condensed water vapor without a single scratch or impact mark from any object. The court floor is covered with an even layer of fine dust from recent renovations, and there are no footprints on it.

The security microphone in the hallway recorded a continuous rhythmic sound of a 'heavy metallic strike' hitting glass, repeating with extreme precision every 1.5 seconds, from 10:05 PM to 10:45 PM.

Heavy mechanical wipers designed to clear snow from the observatory glass (the crime scene) were found turned on. As they descend, their metal arms forcefully strike the lower frame of the glass at a rate of exactly one wipe every 1.5 seconds.

The elevator malfunctioned and completely stopped between the first and second floors from 10:00 to 10:50. The external tracking device recorded continuous walking movement around the outer garden perimeter without entering the building throughout the evening.