Look at the desert again
From Create Your Own Story
The sniper takes his next shot. "Did you see him?" Amir asks, seeing another freedom fighter fall by the already wounded one. You didn't see where the shot came from, there was no sand thrown up from the muzzle blast, and there were no footprints in the sand. "He hit another soldier. We have to find the bastard."
There was no trace of the sniper at either possible vantage spots. Even though there were no signs of him in the sand, you still figure it's more likely he's there than him using the barren and rocky mountains for cover.