It was among the most traumatic days in the F.B.I.’s history: On Feb. 2, 2021, two agents were killed when a suspect in a child abuse case opened fire on them as they tried to search his Florida apartment.
This week, the bureau announced the outcome of the investigation the agents were part of — which had grown into an international operation following their deaths — saying it had resulted in 98 arrests and 45 convictions of members of an online pedophile ring in the United States and Australia.
Nitiana Mann, the F.B.I. legal attaché for Australia, stressed the global nature of the battle against child abuse. “The complexity and anonymity of these platforms means that no agency or country can fight these threats alone,” she said in a statement.
At a joint news conference between the two countries’ law enforcement agencies in Australia, Ms. Mann said that the F.B.I. had made 79 arrests in the United States, resulting in 65 indictments and 43 convictions. She added that the bureau had sent information and evidence related to the pedophile ring to law enforcement agencies in scores of countries.
In Australia, the police have charged 19 men and convicted two, and removed 13 children from harm.
The men were “members of a technologically sophisticated online child abuse network” who shared pedophilia materials through the dark web and used encryption to avoid detection, said Helen Schneider, a commander with the Australian Federal Police.
In 2021, two F.B.I. special agents involved in the case, Daniel Alfin and Laura Schwartzenberger, were killed while executing a search warrant in Sunrise, Fla., near Fort Lauderdale.
The suspect, David L. Huber, opened fire as the agents approached his apartment, killing them and injuring three others, the F.B.I. said. Mr. Huber was found dead inside the apartment after having apparently taken his own life.
It was the first time F.B.I. agents had been shot dead in the line of duty since 2008, when a special agent, Samuel S. Hicks, 33, was killed while serving a search warrant near Pittsburgh.
“After their murder, the F.B.I. commenced an international operation targeting offenders on the platform,” the Australian police said in a statement.
The Australian operation began in 2022 when the F.B.I. shared information about local members of the network who were sharing — and in some cases creating — pedophilia materials, Commander Schneider said.
It was a “complex investigation,” she said, because members of the network used software to anonymously share files and chat on message boards, the police said.
“The lengths this network went to avoid detection is an indication of just how dangerous they were,” she added.
Some of the men had been committing offenses for over 10 years, Commander Schneider said, adding that many were experienced in computing and programming, or worked in information and communication technology positions.
One of the men convicted in Australia was a public servant who pleaded guilty to 24 charges and was sentenced to 14 years in prison, the Australian police said. The other was a call center operator who was sentenced to five years’ imprisonment after pleading guilty to possessing an estimated five terabytes of materials depicting child abuse.
Some of the 13 children removed from harm had been abused, while others were taken as a safety precaution, the Australian police said.