Detective Miller met me in the second-floor lobby with a magnetic key card already in his hand.

“The forensic audio unit finished twenty minutes ago,” he said, holding the heavy door open.

“Technician Arnie is set up in booth three.”

The soundproof room smelled of warm electronics and carpet cleaner.

A sound technician named Arnie sat in front of two high-definition monitors showing two green sound waves.

Detective Miller pulled out a folding metal chair for me near the main console.

“Mrs.