Paddock bought other ammunition at the show, but he couldn’t obtain the tracer ammunition — bullets with a pyrotechnic charge that, when the round is fired, leaves an illuminated trace of its path — because the vendor didn’t have any to sell, the official said…

The official explained that if Paddock had tracer ammunition, he would have had a more precise idea of where his shots were going in the darkness, and could have been more accurate.

But tracer rounds also could have allowed police to see more quickly where he was firing from, CNN law enforcement analyst James Gagliano said.