"Our people have asked. The security guard said that he didn't find anything unusual recently, and the surveillance cameras in that building were always broken, so he stopped fixing it later."
"It's normal that it's broken, and it's very likely that Gardner and the others broke it so that they wouldn't be discovered. How could he allow a camera to record his activities all day long? But the Death Judge took advantage of this. We can be sure that the Death Judge used a soundproofing material," Ross said.
"I agree."
"Then what would it be?"
"What kind of device could achieve this effect? The last time it was in an abandoned warehouse near the downtown area, but no one heard it."
"Could it be soundproof vacuum glass?"
While everyone was guessing, Judy, who had been tapping on the keyboard non-stop, tapped on the enter key with her slender fingers.
"Done!"