At a campaign rally in Butler, PA, former President Trump narrowly escaped a potentially fatal shooting due to a series of shocking failures by the Secret Service. Despite having advanced technology at their disposal, miscommunication and equipment malfunctions left agents unaware of a gunman on a nearby rooftop. The Secret Service missed crucial chances to detect and stop the threat, including turning down a local drone offer and failing to boost communication signals. The tragic incident, where one attendee died and Trump was injured, highlighted the agency’s alarming struggle to effectively use modern technology, leading to one of its biggest security lapses in decades.

After a week of mistakes, the officers protecting former President Donald J. Trump at a campaign rally in Butler, Pennsylvania, had one last chance to do their job right. That chance lasted about 30 seconds.

It started when a local police officer looked over the roof of a warehouse near the rally and spotted the suspicious man, Thomas Crooks, they had been searching for. After 90 minutes of confusion, the officer finally found him.

“Long gun!” the officer shouted over the local police radio, according to testimony from the Secret Service this week.

This urgent message should have gone to a command center shared by the local police and the Secret Service, and then to agents near enough to protect Mr. Trump. They still had a chance to stop an assassination attempt.

But the message never reached the Secret Service, and 30 seconds later, Mr. Crooks fired his first shots.

This failure in communication was just one of many problems with the technology meant to protect Mr. Trump on July 13. Some technology failed, some wasn’t used properly, and some was never deployed at all.

The Secret Service had turned down an offer to use a surveillance drone at the rally site. They also didn’t bring a system to boost their signals in an area with poor cell service. Even some of the equipment they did bring, like a system to detect other drones, didn’t work when needed.

As a result, a 20-year-old gunman had the advantage over a $3 billion federal agency.

Acting Secret Service director Ronald Rowe Jr. told Senate lawmakers this week that the agency had tools that could have spotted Mr. Crooks and let agents question him before the shooting, but they failed to use them correctly.

“That has cost me a lot of sleep,” Mr. Rowe testified. “I struggle to understand it, and I have no explanation for it.”

Mr. Trump was injured in the shooting, and three rally attendees were also shot, one fatally. This was one of the biggest failures of the Secret Service in decades. Mr. Rowe couldn’t understand why the Secret Service didn’t secure the warehouse Mr. Crooks used, which was only about 450 feet from Mr. Trump’s podium, or why no sniper was on its roof.

But the problems weren’t just about where to place personnel. Current and former Secret Service officials said the agency has long struggled to adopt new technology quickly.

“We are living in 2024,” said Mike Matranga, a former Secret Service officer who now runs a security firm. “Why is the government the last to develop and use technology to their advantage?”

Having technology doesn’t guarantee safety, but it can be a crucial backup, especially in times of increased political violence and stretched-thin Secret Service staff due to a presidential election.

Government audits for decades have criticized the Secret Service for being slow to embrace technology, relying on an outdated model of agents using their own weapons and bodies to protect presidents and other high-profile figures.

Nine years ago, after gunshots were fired near Vice President Joseph R. Biden Jr.’s home, Jason Chaffetz, the House Oversight Committee chairman at the time, asked to see footage of the incident.

But the Secret Service director showed up empty-handed, saying, “We don’t have cameras,” Mr. Chaffetz recalled. His committee issued a harsh report that year, saying the agency needed urgent reform.

Congress has steadily increased the Secret Service budget over the past decade, but the agency spends only about $4 million a year, less than 1 percent of its funding, on research and development for new security tools. For next year, they asked for even less funding for research—only $2.2 million.

Anthony Guglielmi, a Secret Service spokesman, said they couldn’t comment on specific technologies used in their protective operations.

It can take years for the agency to evaluate new technology, get approval and funding, and then train personnel to use it, said Chris DeMunbrun, a former Secret Service officer who resigned in 2017 out of frustration with the agency’s slow progress on new tools.

Concerns about civil liberties have also prevented the agency from using facial recognition software widely, even though it’s common in private venues like casinos. This software could help quickly identify known threats, although it wouldn’t have helped with Mr. Crooks, as he wasn’t previously identified as a threat.

The agency has also been slow to adopt less controversial tools, such as drones to monitor rooftops where a sniper might hide. Several companies sell software that can quickly identify exposed guns in security camera footage, which is used in places like Navy Pier in Chicago.

“These situations are incredibly complicated,” said Sam Alaimo, a former Navy SEAL and co-founder of ZeroEyes, a company that provides gun-detection software to many clients, including the Pentagon. “But we build our system to pick up the gun before the first shot is fired.”

Embarrassingly, the Secret Service failed to properly use some technology they did have at the rally.

Mr. Rowe admitted that the agency failed to deploy counter-drone technology successfully when Mr. Crooks launched a drone there. These systems are now widely used at major public events like the Super Bowl and can track unauthorized drones and even disable them.

The Secret Service had planned to use a counter-drone system at the rally site, but the communications network it relied on was overwhelmed by the crowd. The system was offline when Mr. Crooks flew his drone over the site undetected for 11 minutes, two hours before Mr. Trump went onstage.

To make things worse, the agency hadn’t set up a mobile communications system or satellite internet to handle the bandwidth problem.

If the system had been working, the Secret Service could have detected Mr. Crooks immediately, as these systems can locate the person flying an unauthorized drone.

“We could have maybe stopped him on that day,” Mr. Rowe testified. “He might have decided, ‘This isn’t the day to do it because law enforcement found me flying my drone.’”

The Secret Service didn’t have its own surveillance drone at the rally and turned down an offer from local police to use theirs. The drone might have spotted Mr. Crooks climbing onto the roof before he could fire any shots.

“We probably should have taken them up on it,” Mr. Rowe said.

The most tragic technology failure was the inability to quickly relay the message that Mr. Crooks had a gun.

“Local law enforcement in Butler told my staff that they had no way of communicating directly with the Secret Service,” Senator Gary Peters, Democrat of Michigan, said during the hearing. This was because they were using different radio systems.

Since at least 2001, when poor communication among emergency responders contributed to the deaths of more than 100 firefighters in the World Trade Center, the federal government has worked to fix this problem.

At the Butler rally, the Secret Service thought they had a solution. They planned to use a command center where urgent threats heard on different radio frequencies could be shared and passed on to Mr. Trump’s security detail. But this system also failed.

“It seems that information was stuck on the state and local channel,” Mr. Rowe said. “Nothing about a man on the roof, nothing about a man with a gun. None of that information reached our network.”

Even investigating the assassination attempt will be harder because the Secret Service failed to record much of the radio communications among certain federal and local law enforcement at the rally.

“Very unfortunate,” said Senator Ron Johnson, Republican of Wisconsin, during the hearing.

“It is, sir,” Mr. Rowe responded, adding that from now on, the agency will record these radio calls “so we have them moving forward.”