There was nothing "sneaky" about it.

He was supposedly friendly with half of the Dallas police force, who he treated to free drinks at his strip joint.

He just walked in as pretty as you please, to watch the fun.

No one searched him, no one questioned him, no one gave it second thought.

But if I remember my facts correctly, no one posted at any of the entrances to the building "remembers" him entering.

So either someone on the Dallas PD just doesn't remember, was afraid to remember, or was in on the plot.

There is precious little about anything in the entire case that we can be totally sure of.