Renee Good was killed on Jan. 7. Alex Pretti on Jan. 24. Federal agents killed both of them, and the administration labeled both of them terrorists — labels that quickly fell apart when the public learned more about each case and saw videos of the shootings.

Yet it was Pretti’s death that broke the dam, galvanizing public sentiment against the federal government’s tactics and forcing a remarkable retreat by the Trump administration.

Gun-rights groups turned on the White House. Republican senators called for investigations. One poll found that support for abolishing Immigration and Customs Enforcement had nearly doubled among independent voters.

Both deaths provoked outrage. But Pretti’s reached further — into conservative circles that had defended the crackdown, and among independents, who had been willing to look away. Why did his death cross political lines that Good’s, for all the anger it generated, didn’t?

It is never possible to say with certainty why one tragedy widens the circle of outrage and another does not. History offers precedents.

George Floyd was not the first Black man to die at the hands of police in 2020. The searing video of his death, however, and the moment it arrived — during heightened unease around police misconduct — turned his killing into a movement. Rosa Parks was not the first person to refuse to give up her seat on a Montgomery, Alabama, bus; a 15-year-old named Claudette Colvin had been arrested after performing the same act months earlier. But it was Parks, for reasons both strategic and circumstantial, whose case became a catalyst. Tipping points are often visible only in hindsight.

Kevin Drakulich, a criminologist at Northeastern University who studies race, crime and public opinion, put it simply: “Renee Good’s death was tragic. Alex Pretti’s is a trend.”

The federal crackdown had already produced casualties elsewhere, including a Mexican immigrant who was shot and killed by ICE agents in Chicago in September. The death did not draw sustained national attention. Minneapolis was different — two killings of American citizens, at close to the same time, in a city that had become shorthand for protest and police violence.

Good’s death brought doubts about what federal agents were doing in Minneapolis into national view, with protests, headlines and the first serious fractures in President Donald Trump’s public credibility on immigration. Then, four days before Pretti was killed, a photograph circulated widely: a 5-year-old boy named Liam Conejo Ramos, wearing a blue bunny hat and a school backpack, being led away by federal agents in a Minneapolis suburb. A child, detained with his father, shortly after being picked up from school. The image widened the cracks.

The accumulation of images and tragedies does not alone explain the difference in responses.

Good was in her car when an agent shot her. Administration officials thus declared her vehicle a weapon, and said she had posed a threat to the agent. Video analysis challenged that account, but could not rule out the agent’s claim that he had feared for his safety.

Pretti left far less room for speculation. He was on foot, filming with his phone, helping a woman who had been shoved to the ground. The administration called him an “assassin,” who had intended to massacre law enforcement officers.

Within hours, video from multiple angles showed him holding a phone, not a weapon, then being tackled, pinned face down and shot multiple times in the back. An agent had already pulled the gun from Pretti’s waistband. Video analysis concluded that the shots had come after Pretti was disarmed and restrained — a sequence that, under standard use-of-force guidelines, may be difficult to justify.

Many viewers saw an execution, not defense against a domestic terrorist. The government’s story collapsed. Still, it is not enough to account for what followed. But a look at who the victims were and how the public perceived them may help explain how opinion was changed.

Drakulich uses a term for the kind of victim the public instinctively sympathizes with: the “ideal victim.” Two attributes make someone fit. “Someone whose life and well-being is broadly valued,” he said, “and someone who people can judge as not bearing any responsibility for their victimization.”

Consider the details that circulated in the days after Pretti’s death. He was not a so-called criminal immigrant, whom officials say they were targeting, but a white American citizen. He was an intensive care-unit nurse at a Veterans Affairs hospital, caring for veterans. A video of him saluting a deceased patient had circulated months earlier. He was a legal gun owner, with a gun permit, and no criminal record. On camera, in the moments before he was killed, he displayed what a former student called his “familiar stillness and signature calm composure.”

He did not run. He came to the aid of a stranger. Masked federal agents killed him nonetheless.

Sarah Gaither, an associate professor of psychology and neuroscience at Duke University who studies identity and perception, wrote in an email that Pretti’s profile “fit widely held cultural cues associated with respectability and being nonthreatening.”

She added that those cues “lowered resistance to empathy among people who might otherwise dismiss criticism of ICE.”

It was not that Pretti generated more sympathy. It was that his profile removed barriers. For people who had needed permission to criticize the agency, Pretti granted it.

For one constituency, Pretti’s death did more than grant permission to criticize. It confirmed a long-held fear.

For decades, the conservative case for the Second Amendment has rested largely on the premise that an armed citizenry is the last defense against government tyranny. National Rifle Association fundraising letters once warned of “jackbooted government thugs.” The language was apocalyptic, the scenario hypothetical.