The small family office that is managing the wealth of the world's richest person and is helping put together the largest-ever acquisition to be carried out by one person is shrouded in secrecy.

On Monday, Musk clinched a deal to buy Twitter Inc (TWTR.N) for $44 billion in a seminal moment for one of the world's most influential public forums.

Musk - who is also the chief executive of electric car maker Tesla Inc (TSLA.O) and aerospace company SpaceX - revealed in a regulatory filing last week that the social media company should reach out to its family office as a point of contact regarding his proposed acquisition.

Yet little is known about the Austin, Texas-based family office that manages Musk's assets. The office is called Excession and the man who helped build it is Jared Birchall, a former Morgan Stanley (MS.N) banker who has advised Musk on his interactions with Wall Street for several years, according to regulatory filings and legal documents. He also hired an investigator to probe a Musk critic that Musk called "pedo guy" back in 2018, according to court documents

Born in 1974, Birchall was hired by Musk from Morgan Stanley in 2016 to work for his family office. Birchall is also the chief executive of Musk's brain chip firm Neuralink, a director at Musk's tunneling firm the Boring Company and a board member at Musk's philanthropic private foundation.

Business registration records with the Texas comptroller of public accounts list Birchall as the manager of Excession as recently as 2021.

Birchall and Musk did not respond to requests for comment.

Birchall's multiple roles are uncommon for a family office manager and illustrate Musk's faith in him, said Raphael Amit, a management professor at the Wharton School.

"Once you appoint somebody to run the family office, that means that you trust him. And Elon wants to set it up in a way that allows him (Birchall) maximum control."

Morgan Stanley led the financing package for Musk's bid for Twitter and advised Musk on the successful deal, culminating several years of relationships the two have built and bolstered by Birchall.

A day after Musk tweeted in August 2018 that Goldman Sachs and Silver Lake would manage his ultimately failed effort to take Tesla private, Birchall messaged Musk to encourage a Morgan Stanley role.

"They've been our best resource on the personal side, by far. They provide you with the largest ($350M) of all the lines and each time we have pressed them for more borrow power or a lower rate, they've come through," he wrote, according to documents disclosed during a trial over tweets by Musk that he was considering taking Tesla private.

Musk responded: "That seems fair."

"Excession" is also the title of a science-fiction novel by Iain M. Banks about artificial intelligence that Musk was seen carrying at a Sun Valley, Idaho, conference in 2015.

Excession the company was staffed by "essentially two people" in 2019, Musk said in a defamation trial at a federal court in Los Angeles at the time. The second person is not known.

It is not unusual to have a small group of people managing a family office, industry sources said, although by contrast, billionaire Jeff Bezos' family office is reportedly staffed by more than 100 people.

There is no regulatory requirement for family offices to publicly disclose their assets or their key personnel, and Excession's holdings and the value of its assets and number of employees could not be learned.

A graduate of Brigham Young University, Birchall started his career working at Goldman Sachs Group Inc (GS.N) in New York in 1999 as a financial analyst, according to his LinkedIn profile. He then joined Merrill Lynch in Los Angeles for about a decade as a wealth manager.

Merrill Lynch discharged Birchall in 2010 for "conduct resulting in management's loss of confidence" that included "sending correspondence to a client without management approval," according to Financial Industry Regulatory Authority (FINRA) records. Reuters could not ascertain more details about Birchall's termination and FINRA and Merrill Lynch did not respond to requests for comment.

Less than a month later, Birchall began working at Morgan Stanley as a wealth manager.

A Morgan Stanley spokesperson said Birchall was well-regarded when he worked at the bank and left on good terms.

Birchall's role has extended beyond finance.

In 2018, he hired a private investigator to look in to a British diver who criticized Musk's idea of using SpaceX's mini-submarine to rescue a boys' soccer team trapped in a cave in Thailand, according to court documents.

When Musk called the diver a "pedo guy" in a response on Twitter, the diver sued him for defamation. In the ensuing trial, it emerged that Birchall, going by the name James Brickhouse, hired a private detective to investigate the diver. Birchall said in court testimony he had an "instinct to protect Musk."

Musk won the case.

"The idea of loyalty, especially in the family office, is profoundly important, said the Wharton School's Amit. "Because you're exposed to the most intimate and private issues that families have."