When Lunden Roberts needed an expert to help prove that Hunter Biden had the money to keep making substantial child support payments for their 4-year-old daughter, her legal team turned to Garrett Ziegler.

Ziegler doesn’t have a degree in personal finance. He doesn’t personally know the president’s son. But Ziegler, whose first job out of college was working as a low-level aide in the Trump White House, has fashioned himself into a Hunter Biden specialist, compiling personal and financial records from anywhere he can get them. Then, his nonprofit posts them online.

Ziegler claims this cache offers the fullest accounting of Hunter Biden’s life, from his battles with drug addiction to his sexual escapades to his business dealings. “In the Western world, I’m confident that nobody has dug into the American first family more than us,” he said recently on YouTube. “I’ve just become obsessed with studying the family.”

Ziegler, 27, enjoys a following of tens of thousands on social media and the attention of conservative media. He has made himself a chief antagonist of the younger Biden, prompting lawsuits, an Internal Revenue Service complaint and other legal pushback from Hunter Biden’s circle.

Ziegler is at the vanguard of a sprawling network of Biden antagonists, from right-wing media organizations to congressional leaders to MAGA activists, that is focused intensely on the president’s son. They see Hunter Biden’s activities as his father’s biggest political vulnerability, a conclusion reflected in the House GOP’s recent decision to launch an impeachment inquiry.

On Wednesday, Hunter Biden sued Ziegler in federal court in California, alleging that the activist had violated privacy laws and calling him “a zealot who has waged a sustained, unhinged and obsessed campaign against [Hunter Biden] and the entire Biden family for more than two years.”

After Ziegler, who served as a staffer for Trump aide Peter Navarro, a MAGA hard-liner and election denier, left the White House in early 2021, he began focusing his attention on President Biden’s son, turning his formidable energy to unearthing every detail he could. Ziegler received some of Hunter Biden’s financial records, saying he got them from someone who worked at Biden’s bank. He has delved into Hunter Biden’s business dealings. He even acquired a copy of the diary of Ashley Biden, Hunter’s sister.

But his biggest project has been mining embarrassing information, including nude photos and videos, from what appears to be a personal laptop that Hunter Biden left at a repair shop in April 2019. Ziegler said in an interview that he got a hard drive with the purported contents of the laptop from Rudy Giuliani before the Jan. 6, 2021, attack on the U.S. Capitol.

In October 2022, Ziegler announced that the nonprofit he founded, Marco Polo, had published a voluminous report on the laptop, claiming to have unearthed at least 459 criminal or regulatory violations. This claim has not been verified, and Hunter Biden’s team dismisses it as absurd. (The Washington Post has also obtained a hard drive purportedly from the laptop and authenticated some of its contents.)

“We want (our report) to be on coffee tables and bookshelves and be brought out whenever you hear something in the news,” Ziegler said in the interview. On his Telegram page, where he has a following of about 100,000, he added, “We believe that it is the deepest digital colonoscopy ever performed on a sitting U.S. first family.”

Ziegler has a smaller following than some better-known conservative firebrands. But that relatively low profile allows him to unleash inflammatory attacks with less scrutiny, said Jared Holt, who researches extremists for the Institute for Strategic Dialogue think tank.

“There’s an incentive for him to take the extra step and to be just a little more outrageous, because it’s the sort of audience he’s cultivated and the part of the ecosystem he fits into,” Holt said.

Some of Hunter Biden’s associates worry that Ziegler, with his sometimes-wild theorizing combined with an encyclopedic knowledge of Hunter Biden’s history, will influence the public discussion as well as the House probes of the president’s son.

Ziegler argues that he is filling a vital role by scrutinizing the Bidens, particularly because in his view Republicans are not going after Hunter Biden hard enough. “The right wing has totally f—ed up this response,” he said. “It’s been frustrating at the pace. Now we’re seven months in, and I don’t think they’ve subpoenaed Hunter.”

To Democrats, Ziegler and his efforts embody all that is wrong with an era when a single individual can use the internet to humiliate and smear his chosen target. Hunter Biden is a recovering drug addict who has experienced tragedy in his life, they say, and whatever his flaws, they have no bearing on the president’s performance.

Ziegler has “shown himself as a reckless, irresponsible chaos agent,” said Rep. Eric Swalwell (D-Calif.), a House Judiciary Committee member. At a hearing in July, Swalwell raised concerns about Ziegler’s postings attacking federal law enforcement agents.

Ziegler contends that his aggressive actions are justified because his ultimate target is not Hunter Biden, but the president. He asserts that Hunter Biden has been involved for decades in shady business deals with China-based firms and the president has known about it, making the senior Biden beholden to China.

“My focus is never on Hunter Biden — it’s only Hunter’s relationship to Joe,” Ziegler said. “My whole obsession with the Bidens starts and ends with Joe. It doesn’t start and end with Hunter.”

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Hunter Biden’s legal team has not taken kindly to Ziegler’s efforts. In his recent lawsuit, Hunter alleges that Ziegler and the other members of his nonprofit illegally hacked into portions of Biden’s laptop that were encrypted, saying they ignored demands to cease and desist, an allegation Ziegler disputes. Ziegler says he would not “honor” cease-and-desist requests in this matter because he believes his actions have been lawful.

Last February, Hunter Biden’s attorney Abbe Lowell challenged the tax-exempt status of Marco Polo’s parent company, ICU, writing to the IRS that it “has operated as little more than a thinly disguised political operation to attack the Biden administration and the Biden family.” Ziegler said that his personal criticism of the Bidens does not reflect the official views of his nonprofit.

Hunter Biden’s friend and benefactor Kevin Morris has also sued Ziegler, accusing him of harassment and doxing. After the child support settlement, for example, Ziegler posted the coordinates of Morris’s plane on his public Telegram page and speculated about Morris’s potential travels. Ziegler’s attorneys have argued in court filings that he was exercising his free-speech rights.

In one of his most notable moves, Ziegler joined the contentious child support case between Roberts, an Arkansas resident, and Hunter Biden over their 4-year-old daughter, Navy. Hunter Biden initially contested his paternity of the girl until a DNA test proved the relationship, and he has said he remembers little of his relationship with Roberts because it occurred when he was in a spiral of drug addiction.

Roberts’s lawyers, in seeking to have Ziegler designated an expert witness, contended in a court filing that he was “an expert in Hunter Biden, his life, finances, personal history, financial history, the Biden Companies, and the manner in which the Biden family interacts interpersonally and financially.”

Hunter Biden’s attorneys initially objected to Ziegler’s inclusion — complaining of his lack of relevant expertise, his “background,” and his purported grudge against the Biden family — but ultimately relented. Ziegler gave a deposition, which remains sealed, but he never testified publicly in the case. Hunter Biden and Roberts ultimately reached a settlement on child support.

More relevant to the just-launched impeachment inquiry is Hunter Biden’s business career, a subject that has been of great interest to Ziegler. Hunter Biden has denied wrongdoing in his financial dealings, and there has been no publicly available evidence connecting his father to criminal behavior.

Federal prosecutors spent more than four years investigating the president’s son, reaching a deal in June for him to plead guilty to two minor tax crimes and admit to the facts of a gun offense. After that deal fell apart, the prosecutor investigating the case was named a special counsel, and he recently obtained an indictment against Hunter Biden on the gun charges, suggesting the case may go to trial. Here’s why Hunter Biden was indicted 3:55 President Biden’s son Hunter was indicted Sep. 14 for allegedly making false statements and illegally possessing a handgun. (Video: Michael Cadenhead/The Washington Post)

Beyond the president’s son, Ziegler’s broader messaging often conveys a far-right worldview that derides certain groups.

He promotes posts of inflammatory memes and conspiracy theories. He has shared rhetoric saying that Christians are better than others and that White people have been particularly persecuted. He has promoted photoshopped images of women he dislikes in compromising positions with Hunter Biden.

Before working in the Trump administration, Ziegler had few ties to politics. Aside from his cousin Ron Ziegler, who was press secretary for President Richard M. Nixon, his family mostly worked in agriculture and insurance, he told his hometown newspaper in Illinois in 2018. He graduated from St. Louis University in 2018 with a degree in economics before moving to Washington. He and his wife, Allie, have since moved back to Illinois, where he portrays himself on social media as a devout Lutheran and family man.

In the White House, Ziegler worked for Navarro, one of Trump’s most outspoken advisers, who was recently convicted of contempt of Congress after he declined to cooperate with the House committee investigation into the Jan. 6 attack. In his White House role, Ziegler wrote reports about Chinese tariffs (which he argued the U.S. should reciprocate), the covid-19 pandemic (which he argued was planned) and the 2020 election (which he argued was stolen).

Ziegler eventually came to the attention of the Jan. 6 committee, which questioned him about his role in a turbulent White House meeting shortly after the 2020 election that featured a confrontation between some Trump associates who were pushing the president to try to stay in power and a group of aides warning against it.

After being questioned by the committee in July 2022, Ziegler unleashed a 27-minute inflammatory tirade on his Telegram page calling the investigation discriminatory against White people and using sexist slurs to describe female ex-colleagues who cooperated with the committee.

“They see me as a young Christian who they can try to basically scare, right?” Ziegler said. Calling the probe “a Bolshevistic anti-White campaign,” Ziegler added that he is “the least racist person that many of you have ever met, by the way.”

He has accused several Biden allies of being Bolsheviks, prompting Jonathan Greenblatt, the chief executive of the Anti-Defamation League, to note that such words are “often used as a code for Jews.” Ziegler rejected any criticism from the group, saying that any ADL position is “probably a good indication of what I believe to be the exact opposite case.”

Ziegler also has posted, on his Telegram page, photos of his targets’ daughters wearing bathing suits or partying with friends, sometimes ridiculing the girls’ appearances. In other posts he has shared with his following, women are mocked for being bad drivers or purportedly being biologically unfit for military combat.

Ziegler said his attacks on the women are legitimate, even if they are private citizens, because their public photos are “degenerate.” He said he does not agree with every post he shares with his followers; he was joking when he forwarded memes about women’s driving skills, he said, but he does not believe women should serve on the military front lines.

Ziegler has also shared posts by white supremacist Nick Fuentes and claimed there is a “war on Whites.” Liberal activist David Brock, whose group Facts First USA has tracked Ziegler’s online comments, said he has warned lawmakers, journalists and others about Ziegler’s rhetoric, urging them to keep their distance. “He doesn’t belong within 100 miles of Congress or a courtroom,” Brock said in an interview.

Ziegler said he does not agree with all of Fuentes’s views, but he does believe that White people are unfairly persecuted, citing government efforts to seek a more diverse workforce. He is a “Christian and a nationalist,” he said, but not a Christian nationalist.

House Republicans are ramping up their efforts to investigate Hunter Biden, culminating in an instruction by House Speaker Kevin McCarthy (R-Calif.) to House committees on Sept. 12 to open an impeachment inquiry into President Biden centered on his son’s business dealings, some of the same areas that Ziegler has probed.

Ziegler said he has made contacts within GOP congressional offices and given them copies of the report on Hunter Biden’s laptop, though he declined to name specific lawmakers.

Some members of Congress, however, have publicly mentioned the report. Sen. Ron Johnson (R-Wis.) said in an interview with NBC’s Chuck Todd that “you ought to read the Marco Polo report where they detail all kinds of potential crimes.” (Todd responded that citing “potential” crimes is “innuendo.”) Rep. James Comer (R-Ky.) told Newsmax the “positive thing” about the report is its inclusion of banking records.

“The response has been obviously grateful” from Republicans receiving the report, Ziegler said. He added: “Sometimes they’ve had an aversion to hearing me out — and then once they looked at our work or site … ,” trailing off.

At one recent congressional hearing, after Rep. Marjorie Taylor Greene (R-Ga.) displayed what appeared to be nude photos of Hunter Biden, Democrats noted that she had displayed the photos in the same order and with similar redactions as in the Marco Polo report. Greene’s office did not respond when asked if the photos came from Ziegler or his nonprofit, but he suggested they did.

“Some of our screenshots in the report were utilized,” Ziegler said in the interview. “So I’ve been somewhat pleased.”