WASHINGTON — When George Piro learned that some of his former colleagues were spreading unfounded rumors about him, he was stunned.

Piro, 55, was a highly decorated agent in the FBI. During his 23-year career, he earned a national intelligence medal for the months he spent interrogating Saddam Hussein, supervised several high-profile shooting investigations and consistently earned reviews that were among the highest for agents who ran field offices.

Now, he stood accused of misconduct by a group of former agents who had been placed on leave and called themselves "the Suspendables." In a letter sent this month to FBI Director Christopher Wray, the group surfaced persistent accusations against the bureau, saying it had discriminated against conservative-leaning agents. The group's letter also falsely suggested that Piro, who once ran the FBI's office in Miami, had played a suspicious role in the bureau's search this summer of Mar-a-Lago, former President Donald Trump's private club and residence in Florida.

"These claims are absolutely false," Piro said in an interview. "I dedicated my life to the country and the FBI. I am disappointed that former agents would spread lies about me."

The attacks on Piro, and his angry rebuttal of them, are emblematic of a toxic dynamic that is increasingly central to Republican Party politics. Trump's supporters — among them, Republicans poised to take over the House next month — have seized on the letter's accusations and stepped up their assaults on the FBI, seeking to undermine the bureau just as it has assumed the lead in an array of investigations of Trump.

Rep. Jim Jordan, R-Ohio, who will be the Judiciary Committee's chair next month, has pledged to investigate what he describes as the politicization of the FBI as well as that of the Justice Department. In a taste of what is to come, the committee's Republican staff released a 1,000-page report last month that asserted that the FBI hierarchy "spied on President Trump's campaign and ridiculed conservative Americans" and that the "rot within the FBI festers in and proceeds from Washington.''

Historically, the FBI's most vocal critics have come from figures on the left, who have accused it of using heavy-handed tactics in investigating groups such as trade unionists or civil rights activists. Conservatives and Republicans have, at least by tradition, supported the FBI and other law enforcement agencies.

A majority of the attacks laid out in the Suspendables' letter to Wray echoed those in the Judiciary Committee's report, which also condemned the bureau for using counterterrorism tactics to investigate conservative parents at school board meetings — an allegation that seemed to have come from a mischaracterization of the FBI's plan to track threats of violence against school board officials.

The report further accused the agency of "helping Big Tech to censor Americans' political speech" — a claim that misrepresented the way the FBI has sought for years to curb online disinformation, especially when it comes from foreign actors. Long before the House report or the letter to Wray were released, Trump and his allies in Congress and the news media were already targeting federal law enforcement officers and demonizing those who scrutinized the former president.

The attacks began in 2018, after federal agents searched the office of Michael Cohen, Trump's personal lawyer, for evidence of campaign finance violations. After the search, Rudy Giuliani, another lawyer close to Trump, went on the warpath. He declared that the FBI's office in New York — with which he had worked closely as the U.S. attorney in Manhattan — had behaved like "storm troopers" in conducting the raid.

Since then, Trump and his supporters have gone after the bureau for its role in investigating his campaign's ties to Russia; for purportedly failing to investigate issues surrounding Hunter Biden's laptop; and for using informants to infiltrate a group of militiamen charged in a plot to kidnap Gov. Gretchen Whitmer of Michigan.

Some critics, including former agents, have attacked the FBI for pursuing those in the mob that stormed the Capitol on Jan. 6, 2021, describing the criminal prosecution of the rioters as political persecution.

This drumbeat of vitriol has created a reflexive reaction against the FBI as nefarious and partisan among large swaths of the right, even as Trump has lost a measure of political support.

"The FBI is the largest criminal gang in the country," right-wing commentator Dinesh D'Souza recently wrote on Twitter, adding, "It's America's version of the KGB or the Chinese state police."

To be sure, the FBI has made several grievous errors in recent years. It failed to follow up on a tip that might have prevented a school shooting in Parkland, Florida, in 2018. It bungled an investigation in 2015 into claims that a doctor for USA Gymnastics had sexually abused young women.

In 2020, an FBI lawyer pleaded guilty to doctoring an email that was used in preparation to ask a court to renew an order to wiretap a former Trump campaign adviser. Questions have also been raised about whether the bureau, which is in charge of preventing terrorism, could have done more to stop the Capitol attack with the use of secret informants it had within two of the far-right groups involved in the riot.

Some recent attacks on the FBI by right-wing officials and figures in the news media seem intended to make money. Rep. Marjorie Taylor Greene, R-Ga., sells "Defund the FBI" baseball hats; Sebastian Gorka, a former Trump adviser, peddles T-shirts reading, "FBI: Fascist Bureau of Intimidation."

The barrage of messaging comes as the bureau itself has faced violence.

In August, an Ohio man, enraged by the search of Mar-a-Lago, tried to break into the FBI's field office near Cincinnati and was ultimately killed in a shootout with local police. Investigators later discovered social media posts he had written encouraging others to kill federal agents.

On Dec. 16, a Tennessee man who was facing charges of assaulting police during the Capitol attack was charged again with plotting to assassinate several of the federal agents who had investigated him. He was also accused of planning an attack on the FBI's field office in Knoxville, Tennessee.

The Suspendables' letter and the House Republicans' report were both apparently drawn from statements by former FBI agents who left the bureau under a cloud and then came forward as self-described whistleblowers. Among them is Steven Friend, a former agent from Florida, who refused to take part in a SWAT raid this summer of a Jan. 6 suspect facing arrest on misdemeanor charges.

"I have an oath to uphold the Constitution," Friend, a 12-year veteran of the bureau, told his supervisors when he declined to join the raid Aug. 24 in Jacksonville, Florida, which he deemed an excessive use of force. "I have a moral objection and want to be considered a conscientious objector."

According to Justice Department records, there was only one Jan. 6-related arrest in the Jacksonville area Aug. 24: that of Tyler Bensch, who was accused of being a member of a right-wing militia group connected to the Three Percenter movement.

What Friend omitted from his account — which was published in the New York Post and widely shared online — was that while Bensch was charged with only misdemeanors, documents in his case say that on Jan. 6, 2021, he posted a video of himself outside the Capitol wearing body armor and a gas mask and carrying an AR-15-style rifle. The documents also say that witnesses told the FBI they had seen photographs of Bensch carrying a similar rifle at other times.

Former FBI agents who have served on SWAT teams said the use of tactical agents during arrests has nothing to do with the charges someone is facing but is based instead on a risk assessment of the suspect.

"When in doubt, you use SWAT," said Robert D'Amico, who served on the Miami tactical team for four years and the hostage team for almost two decades. "You never let the charges dictate the tactics."

Last year, two FBI agents were killed and three more were wounded while serving a search warrant in a case involving child pornography in Florida. The suspect did not have a violent history and had been deemed low risk. The deadly episode illustrated the dangers of serving warrants or arresting suspects considered not threatening. The agents worked for Piro.

Friend's lawyer said his client objected to the SWAT team arrest because he wanted to "de-escalate" the situation and avoid what he described as another Ruby Ridge — a reference to a botched FBI raid on a white supremacist compound in Idaho in 1992 that has becoming a rallying cry for far-right extremists.

The FBI declined to comment on the attacks against Piro, but three former and current law enforcement officials, speaking on the condition of anonymity to discuss personnel matters, said he was not under investigation when he retired from the bureau.

Piro said he was depressed by how some former agents had turned on the bureau.

"I am saddened by their behavior and their total disregard for those who are working for the FBI," he said, "and those who came before them to make the FBI the premier law enforcement agency in the world."