Taylor nodded.

Returning to the van, we found Taylor’s phone and earbuds tossed onto the passenger seat. He had accessed the data from the mic on his phone and was listening in to the live feed while analyzing the audio levels from what the mic had recorded up until then. Where the levels were flat indicated no noise; a higher volume suggested the mic had picked something up, and we listened to about ten minutes of audio—predominantly footsteps, David on his way from his office to the ...