The open window is in the building adjacent to the roof Crooks was on. If someone was in that window, he couldn’t help but see Crooks. Actually, he would also have had a clear view of the stage, too.
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30,000 people make a lot of noise.
If Snipers listened for noises behind them and in the woods, they wouldn’t be snipers for long.
Why didn’t Crooks point his weapon at the crowd pointing at him and getting Police? He ignored them because the training is to focus on the target.
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The open window is in the building adjacent to the roof Crooks was on. If someone was in that window, he couldn’t help but see Crooks. Actually, he would also have had a clear view of the stage, too.
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The two story building was not exactly aligned up with the roof line of the single story buildings, but the window visible at the end of the two story building suggests there would be a similar window arrangement on the other end of the building, This end window along with the numerous side windows would have permitted security to visually cover the entire roof surfaces of the lower story buildings. Why on earth the security would be situated back inside and away from these windows is as lame brain dead as saying the roofs of the one story buildings were too steep for security to post.