I thought it might’ve been the bearded guy in the 2nd photo or the stocky woman next to the black guy in the leftmost photo.
I dunno.
Details show different. Working L>R
Timing show photo first with DF hand about to touch wall. Photo 2 and 3 come after that shown by DF hand.
Next detail in photo second shows stocky female gone and black man studying his phone.
Photo third shows a corner of the cinder block wall in the hall directly across.
My conclusion is the black fellow in photo 2 starting his camera and -photo 3- snapping pictures as he leaves down the hallway.
There is in photo first another (seeming) black gentleman that looks like he has a phone to his ear. He is not the photographer as he us gone? from photo 2 and his photo would have shown some of the wall he us backed against.