“Trump is the man,” Thomas “Tom” Barrack, a wealthy investor friend of Donald Trump’s, wrote to someone in a foreign government, in 2016, as Trump’s likelihood of being named the Republican nominee for president began to become a certainty. Barrack added, cryptically, that someone called “HH” should be ready to travel.

The meaning of those words, and the intent behind them, are at the center of the latest court case to roil Trump’s circle. Prosecutors have said that the “HH” in Barrack’s email referred to His Highness Mohammed bin Zayed Al Nahyan, the current leader of the United Arab Emirates, and that Barrack was trying to secretly and illegally trade his access to Trump’s ear for the graces of the Emirati government and its vast pool of investment money.

The US government has charged Barrack, whose trial began last month in New York, with acting as an unregistered foreign agent – lobbying Trump on the Emirates’ behalf, over several years, and feeding confidential information back to the small but powerful Middle Eastern petro-state.

Barrack denies the charges against him, which his attorneys have called “nothing short of ridiculous”. They argue that he was trying to be useful as an intermediary, and was engaged in wholly legal wheeling and dealing. “He did things because he wanted to,” Michael Schachter, a defense lawyer for Barrack, said last month. “The idea that Tom Barrack was controlled by anybody is nonsense.”

Although there is no evidence that Trump was aware of Barrack’s alleged wrongdoing, the case adds to the mounting pile of legal woes afflicting the Trump camp. They now include Congress’s hearings on the US Capitol attack, a federal investigation into whether Trump illegally kept classified White House documents, a New York state lawsuit accusing him of fraudulent business practices, and a New York state prosecution of Steve Bannon, the former Trump adviser, for allegedly defrauding people who donated to a campaign to build a wall on the Mexican border.

The prosecution of Barrack as an alleged semi-spy for the Emiratis is yet another scandal involving foreign influence on the Trump campaign and administration, which were dogged by impeachment proceedings and special investigations over alleged collusion with Russia and inappropriate pressure on Ukraine.

Barrack co-founded a pro-Trump fundraising group, Rebuilding America Now, with the lobbyist Paul Manafort, who later pleaded guilty to bank fraud, witness tampering, and conspiracy to defraud the United States in charges stemming from the Robert Mueller investigation. The US senate intelligence committee has said that Manafort’s interactions with Russian nationals constituted a “a grave counterintelligence threat” and created openings for “Russian intelligence services to exert influence over, and acquire confidential information on, the Trump campaign.”

Mike Flynn, Trump’s national security adviser during his campaign and his first White House national security adviser once in office, was forced to retroactively register as a foreign agent after admitting that he had done lobbying work for the government of Turkey. He resigned less than a month into his tenure, after serious questions were raised about his close relationship with the Russian ambassador.

Barrack has been a business associate and confidant of Trump’s for decades. They met through their mutual work in real estate, and in the 1980s and 1990s, Barrack, Trump, and the socialite and sexual predator Jeffrey Epstein formed a trio of “nightlife musketeers”, the journalist Michael Wolff wrote in his book Fire and Fury: Inside the Trump White House. When Trump ran for president, Barrack, working with Manafort, raised millions of dollars for his campaign.

Barrack began colluding with the Emirati government before Trump had even taken office, according to prosecutors. In May 2016, Manafort gave Barrack a draft speech of Trump’s and, according to the New York Times, asked, “Are you running this by our friends?”

Barrack shared it with Saudi and Emirati officials. “They loved it so much! This is great,” Barrack’s Emirati contact, Rashid al-Malik, told him. As the speech was revised, Barrack worked to make sure it remained favorable to the Emirates’ geopolitical interests.

Barrack, who is of Lebanese descent and speaks Arabic, liked to think of himself as someone who understood the Middle East better than most American officials and could act as a broker between the Gulf states and the US.

This became particularly salient when Trump, shortly after entering office, angered the Middle Eastern world by banning people from numerous Arab and Muslim-majority countries from entering the US. Saudi Arabia and the Emirates were also keen to influence Trump against their rival, Qatar.

Less than two weeks after Trump entered the White House, Barrack tried to persuade Steve Bannon to support a plan that would supply high-level American nuclear technology to Saudi Arabia. Barrack argued that this would help “balance the current noise” caused by Trump’s travel ban.

At the same time, according to the New York Times, Barrack was trying to get Saudi officials to pressure the US to appoint Barrack as a Middle East envoy. The nuclear plan never happened, and Barrack was not made an envoy.

From 2016 to 2019, Saudi Arabia and the United Arab Emirates disbursed about $1.5bn to Barrack’s real estate company, Colony Capital, which is now called the DigitalBridge Group. In 2017, for example, Emirati sovereign wealth funds put $374m into two deals arranged by Colony Capital.

In February 2019, while at a conference in Abu Dhabi, Barrack appeared to excuse Saudi Arabia’s murder of the Saudi-American journalist Jamal Khashoggi. “Whatever happened in Saudi Arabia, the atrocities in America are equal, or worse,” he said, though he later apologized for the remark.

Barrack’s ties to the Gulf states were reported by the US House Committee on Oversight and Reform in 2019. “With regard to Saudi Arabia,” the committee’s chair, Elijah Cummings, said, “the Trump administration has virtually obliterated the lines normally separating government policymaking from corporate and foreign interests”.

As foreign influence on Trump’s court became the subject of increasing scrutiny, Barrack came under investigation. Prosecutors have accused him of deceiving federal agents who interviewed him in 2019.

The messy case has sucked in other people. Barrack’s Emirati contact, al-Malik, was charged as an accomplice, but has avoided trial because he is not in the US. Barrack’s assistant at Colony Capital, Matthew Grimes, has been charged with a lesser crime related to lobbying.

Barrack “illegally provided a foreign nation with access and influence at the highest levels of the United States government,” a prosecutor, Hiral Mehta, declared during the government’s opening statement last month. “The actions they took were not business; they were crimes.”

Witness testimony recently began, with Rex Tillerson, Trump’s former secretary of state, called to testify. Tillerson said that he did not know Barrack well, that he did not know of his connection to the Emiratis, and that his influence on the US state department was minimal.

Regardless of the outcome of Barrack’s corruption trial, it seems unlikely that it will do anything to improve the already murky legacy of the Trump White House.

“I believe it unprecedented in any US administration for so many of the closest circle of persons around the president to have been shown to be conmen, grifters and base criminals,” Patrick Cotter, a former federal mob prosecutor, told the Guardian in 2020.