Just another point of view to ponder.
A lot of people are excoriating the Secret Service as having failed.
Back in April, when Bidan visited Balitmore, a customer of mine was escorting
Biden's entourage (lead of motorcycle brigade).
He told me that the USSS not only had the officers motorcycles searched, as well as their persons, the USSS had them staged 6 hours early, just waiting.
And again, the USSS searched their motorcycles and person's about one half hoir before Biden's arrival.
The USSS is very thorough and they allocate positions and tasks to local law enforcement.
That being said, the building the Crooks kid shot from was most likely allocated to local law enforcement who's task was to secure the perimeter and deny access.
When, of if, a USSS agent saw someone on that building's roof, the USSS agent 's first thought would have been something like, "well that's odd, but that building is secured by so-and-so law enforcement". This is also how the USSS sniper nuetralized the threat so quickly.
The breech of security came from local law enforcement, not USSS.