Thomas Matthew Crooks should never have been able to get on a roof fewer than 150 yards from former President Donald Trump, let alone take several shots at him — almost killing him, wounding two rallygoers and murdering a third. The shot was an inch away from a national and international catastrophe, and the institutions tasked with securing the event must be held accountable.

Butler County District Attorney Richard Goldinger called the situation "embarrassing,” and that’s the kindest word he could have used. Public statements by law enforcement agencies are already devolving into subtle blame-shifting. Local police have wondered why the Secret Service agents perched above the rally stage didn’t spot the gunman, and the Secret Service has suggested local law enforcement was tasked with securing the area beyond the rally grounds.

And now we know that not only bystanders but other law enforcement personnel saw a man with a gun and identified the risk. The one local officer who climbed up to the roof to investigate was unarmed. The Secret Service countersnipers — who did not need authorization to shoot at an active threat —had the responsibility to protect Trump and the people around him. How is it possible that they still hesitated to take their shot until Crooks had already fired?

Further, how was that roof not secured by law enforcement to begin with? Secret Service director Kimberly Cheatle told ABC News that the sloped nature of the roof made it too dangerous to station officers there. This is ludicrous: It wasn’t too dangerous for a 20-year-old novice marksman.

And isn’t accepting danger part of being in the Secret Service? Agents put their body between the president and a bullet. They can take the small risk of sliding off a roof. Indeed, the roof where they did station snipers is steeper than the one where they didn’t station them.

In the face of these lapses, Biden has rightly called for an independent investigation into his campaign rival’s security measures on the day of the rally. This must begin at the Secret Service and include all other agencies that were part of the Butler detail, including the Pennsylvania State Police. The investigators must look very carefully at the thoroughness of planning — why was so obvious a threat left unguarded? — and the efficiency of communication during the event itself.

Even if the Secret Service had given local or state agencies the responsibility for the rooftop, the entire operation is ultimately that agency’s responsibility. The Secret Service is the highly trained, highly resourced agency the nation depends upon to protect its presidents and presidential candidates. It is hard to imagine how Cheatle can remain the director.

Crooks was not a master assassin. He was a young man with inscrutable motives who decided to take a shot at the former president. If all it takes is one novice to get inches from plunging America into a historic political crisis, a crisis of competency in the nation’s security agencies already exists. This cannot happen again.