Almost two years after the January 6, 2021, attack on the U.S. Capitol, the sprawling federal investigation into the riot continues at an “unprecedented speed and scale,” with more than 950 people arrested, U.S. Attorney General Merrick Garland said Wednesday.

That number represents less than half of an estimated 2,000 to 2,500 supporters of former President Donald Trump believed to have breached the Capitol as lawmakers met to certify the results of the 2020 presidential election.

But Garland, the nation’s chief law enforcement officer, said the Justice Department remained determined to bring every lawbreaker to justice.

“We remain committed to ensuring accountability for those criminally responsible for the January 6 assault on our democracy,” Garland said in a statement. “And we remain committed to doing everything in our power to prevent this from ever happening again.”

David Sundberg, assistant director in charge of the FBI Washington Field Office that has been leading the federal investigation, indicated the probe could take years.

“In the months and years to come, the FBI Washington Field Office will continue to partner with U.S. attorney’s offices across the country to bring to justice those who attempted to use violence to substitute their will over the will of the people,” Sundberg said in a statement.

FILE - A mob of supporters of then-U.S. President Donald Trump storm the U.S. Capitol building in Washington, Jan. 6, 2021.

FILE – A mob of supporters of then-U.S. President Donald Trump storm the U.S. Capitol building in Washington, Jan. 6, 2021.

While most of those arrested so far in connection with the January 6 attack have faced misdemeanor charges such as entering or remaining in a restricted federal building, others have been prosecuted for more serious crimes.

Among them are Stewart Rhodes, founder and leader of the Oath Keepers, an anti-government militia, and Kelly Meggs, leader of the group’s Florida chapter. Both were found guilty of seditious conspiracy in November.

The charge carries a maximum sentence of 20 years in prison.

Separately, five members of the Proud Boys extremist group, including its chairman, Enrique Tarrio, are on trial on seditious conspiracy charges in federal court in Washington.

Prosecutors say the two pro-Trump groups mobilized their members to storm the Capitol.

Jordan Strauss, a former federal prosecutor, said the Justice Department appears to be taking “very close to a zero-tolerance approach” to prosecuting the perpetrators of the January 6 attack.

“They seem to be going after 100 percent of those who they believe committed crimes,” said Strauss, a managing director at Kroll, a corporate investigation and risk consulting firm.

In its final report, the congressional committee investigating the circumstances leading up to January 6 placed the blame for the attack on Trump, accusing the former president of engaging in a “multi-part plan” to overturn the result of the presidential election.

Trump slammed the report as a “witch hunt.”