This miscreant had all this expertise in his head to penetrate world class security. Lone wolf.

state, county, and local police had primary security responsibility outside the event. The shooter himself was outside the USSS zone. A local police officer was checking reports of someone on a roof in their zone when the shooting happened. While it was not explicitly stated, the inference I drew is that the officer's presence and retreat when a weapon was pointed at him, may have rushed the shooter before the first round was fired.

FACT: The local police force was tasked with covering the area of the building the shooter used. (according to the S.S)

FACT: The building had been identified as an area that required law enforcement to guard/monitor.

ACCEPTED AS FACT: An officer attempted to intercede but retreated when he came under the aim of the shooter.

OCCAMS RAZOR: The local police force failed to prevent one person from entering/ scaling the building, a person who intentionally tried to avoid attention for his purposes. He sneaked by the cops. Is that so hard to accept?

I think the cops need to explain that - at least.

Were they checking people's bags, did they use magnetometers? The photo I saw of the kid, he didn't look very tall, maybe even slightly short. That weapon had to be longer than his arm.

There are so many unanswered questions.

Sufficiently. The officer(s) in the area either allowed themselves to be distracted, or the instructions they had, everything they were responsible to cover was too much.

I say it’s the simplest solution to the questions. That is my understanding of Occam’s razor.

When I say the instructions to the officers in that area may have been badly designed. I would blame the local departments for that or suspect them of doing it poorly I mean.

So he had to know how to put it together once he got into the building.

I still find it weird that the cops weren't checking people's bags, AND they allowed random people to just walk in with no ID. This building was very CLOSE to the stage area.

How was the kid able to find a way up to the roof? Aren't those stairways or access ramps locked up under normal circumstances?

There's just a lot of planning that went into this, and the kid must have had help from somebody. Doesn't it seem that way? Occam's Razor doesn't account for everything.

How about justice?