WASHINGTON — The acting director of the Secret Service was incensed at what had happened that July evening. “What I saw made me ashamed,” Ronald Rowe Jr. said. “I cannot defend why that roof was not better secured.”

The unguarded roof, easily within shooting distance of the rally stage, is just one of the myriad questions behind the worst Secret Service security failure in decades. The more that investigators unpack from that day, the more missed opportunities that could have prevented the attack are revealed.

As the United States grapples with a second attempt on Donald Trump’s life, in Florida, there remains a reckoning to be done from the Pennsylvania shooting on July 13 that killed one man and wounded three — the ex-president among them.

The Secret Service is a well-funded, historically elite force with a mission to keep presidents and other higher-ups safe — whether they’re out for a bicycle ride, attending a world summit, visiting a war zone or campaigning.

But at the farm show grounds, a young nursing home aide with a rifle he borrowed from his dad outmaneuvered authorities for more than 90 minutes before firing the shots that came millimeters from killing Trump.

There are plenty of unanswered questions. Including a key one: What possessed 20-year-old Thomas Matthew Crooks to try to kill the former president?

This anatomy of an attempted assassination is based on an AP review of dozens of documents, text messages and video, plus interviews on the record and from law enforcement officials who spoke to AP on condition of anonymity to discuss investigations that are still getting going.

Related Article: Secret Service failures before Trump rally shooting were ‘preventable,’ Senate panel finds

Rowe’s voice grew louder at the July 30 Senate hearing as he squared off with lawmakers who wanted him to fire somebody — anybody — who had been on the ground that day. It wasn’t enough for them that the agency's chief, Kim Cheatle, had resigned a week earlier. But Rowe dug in.

“I will not rush to judgment," he said, snapping at a senator. “People will be held accountable, and I will do so with integrity.”

Last week, the Secret Service released a five-page document summarizing conclusions in a report not yet completed. Among the findings: The Secret Service did not give clear guidance to local law enforcement partners at the rally. It did not correct line-of-sight problems that left Trump open to sniper fire. And some of the agents on duty that day were complacent.

A bipartisan report from the Senate Homeland Security and Governmental Affairs Committee made public Wednesday was more blunt if not scathing. It found “USSS failures in planning, communications, security, and allocation of resources for the July 13, 2024, Butler County rally were foreseeable, preventable, and directly related to the events resulting in the assassination attempt that day.”

Butler County, on the western edge of a presidential swing state, is a Trump stronghold. It was designed to be a typical Trump rally — outdoors at the Butler Farm Show grounds with big red barns, wide-open fields and bleacher seating.

Three days after the rally was announced, Crooks registered to attend. He also searched online for “how far away was Oswald from Kennedy?”

Lee Harvey Oswald shot and killed President John F. Kennedy in Dallas on Nov. 22, 1963, while he was riding in an open convertible. Oswald concealed himself on the sixth floor of the Texas School Book Depository. The Warren Commission determined he was 265.3 feet from Kennedy when he fired the fatal shot.

Crooks would fire from about double that distance. But guns have evolved since then, and the AR-style weapon Crooks borrowed from his father shoots faster and more easily than anything Oswald had on him.

There were roughly 155 law enforcement officers at the rally that day. That included a Secret Service counter-sniper team, a Butler County SWAT team and uniformed officers. Hundreds of Trump supporters gathered to hear him speak.

The FBI says that after Crooks turned up at the site on that sunny Saturday afternoon, he flew a drone for about 11 minutes up and around the area and was getting the view directly on the controller he used. The Secret Service did not deploy its drone-detection system until later in the afternoon.

The first reported sighting of Crooks was at 4:26 p.m., more than 1½ hours before Trump would begin speaking.

At 5:38 p.m., a Beaver County sniper, stationed inside the building where Crooks would later shoot from the roof, sent photos of Crooks to the local team’s group chat. Secret Service sniper teams were posted on the roof closest to where Trump was to speak, but officials say the teams were never notified.

Bystanders eventually saw Crooks again. They took mobile phone video of him pulling himself up to the top of the roof and slithering into position. They called the cops. By 6:08 p.m., law enforcement had eyes on Crooks again.

Three minutes later, a local officer was hoisted up the squat roof by another officer, who saw Crooks with the rifle, laying down and pointing the weapon toward him. “He’s armed,” the officer radioed to his squad. “He’s got a long gun.”

That message did not get to the Secret Service. The shots were fired 30 seconds later.

Days after the shooting, Trump spent more than 10 minutes of his speech to the Republican National Convention giving vivid detail of what happened to him on the “warm, beautiful day in the early evening in Butler Township in the great Commonwealth of Pennsylvania.”

The crowd was rapt. Some in it would later don ear bandages like his in a show of support. Even some of Trump's fiercest critics conceded his turn on the stage in Butler had been masterful — raising his fist as blood trickled down his face, mouthing “fight” as he was hustled away.

Trump told his convention “the assassin’s bullet came within a quarter of an inch of taking my life.”

Those who tuned in at the start of his speech saw a man trying, for once, to reach a wider audience than his MAGA millions. “The discord and division in our society must be healed,” Trump said. “We must heal it quickly.”

That didn’t last long. Most of the rest of his speech returned to standard operating procedure — the bombast, the falsehoods, the depictions of a United States rotting under Democrats.

The temperature has not cooled since. After the second attempt at his Florida golf course, Trump and his allies now are trying to lay blame directly on Democratic rhetoric for making him a literal target.

In that case, officials said, the suspect did not get off any shots, never had Trump in his line of sight and fled from the scene after a Secret Service agent spotted and fired at him. He was later captured.