With a $50m (£39.5m) donation made on 31 May, 81-year-old Timothy Mellon has become the largest donor to the former president so far during this electoral cycle. Mr Mellon, the heir to the Pittsburgh-based Mellon banking family, also has been the biggest donor to independent candidate Robert F Kennedy’s campaign.

The BBC has contacted Mr Mellon for comment about his political donations. Known as a recluse, the Wyoming-based Mr Mellon avoids the spotlight and social circles of other US billionaires.

Here’s what we know.

According to Forbes magazine, Mr Mellon is a descendant of Thomas Mellon, an Irish immigrant who amassed a fortune in real estate and banking after arriving in the US in 1818.

The Mellon family – which also included Mr Mellon’s grandfather Andrew, a former US treasury secretary – is today worth over $14bn (£11bn). Forbes estimates that that the Mellons are the 34th richest family in the US.

Born in 1942, Mr Mellon attended Yale University where he studied city planning. His father was a major donor at the school and provided the funding to establish the Yale Center for British Art – the largest collection of British art outside the United Kingdom.

In 1981, Mr Mellon formed Guilford Transportation Industries, a holding company named after his hometown of Guilford, Connecticut. It quickly bought up three major railways that stretched from Canada, through New England and into the mid-Atlantic region of the US.

The firm, which had maintained its chief focus on railroads, pivoted in 1998 when it bought the brand of the famed – but long bankrupt – Pan American World Airways. Perhaps influencing the purchase, Mr Mellon had developed a love for flying around this time – logging more than 11,500 hours in the cockpit.

“As owner of the company [Pan Am] and with the skill necessary to do the job, he became a commercial pilot and quite literally kept the American institution that is Pan Am flying,” reads a synopsis for an upcoming autobiography due to be published in 2025.

Through much of this, he served as trustee of the Andew W. Mellon Foundation, stepping down in 2002 after 21 years. Three years later, in 2005, Mr Mellon left his native Connecticut for Wyoming. He has lived there since, avoiding the spotlight and only rarely speaking to the media.

Even before his recent donation to the Trump campaign, Mr Mellon has a history of donating to conservative candidates and causes. In 2010, Mr Mellon donated about $1.5m to the state of Arizona to defray the legal costs to defend SB 1070, a controversial anti-immigration bill.

More recently, Mr Mellon helped bankroll Texas governor Greg Abbott’s construction of a wall along the Mexican border, providing more than $53m for the project in 2021. He also has given money to various Republican-aligned super PACS – or “political action committees” – to support conservative candidates.

Mr Mellon highlighted some of his political views when he wrote a self-published 2015 memoir. In it, he condemned what he termed “Slavery Redux” social safety net programmes.

Mr Mellon also wrote that black voters were awarded “freebies” in exchange for “delivering votes”. He claimed this “largess” is “funded by the hardworking folks…who are too honest or too proud to allow themselves to sink into this morass”.

In exchange, he claimed, black Americans became “more belligerent” and “slaves of a new master, Uncle Sam”. Mr Mellon, however, has occasionally made small donations to Democrats, including $2,700 for progressive New York representative Alexandria Ocasio-Cortez’s 2018 campaign.

He told Bloomberg News in 2020 that she tried to return the donation, but that he refused to cash the cheque.

Mr Mellon also expressed admiration for Trump during that rare interview, telling Bloomberg that “he’s done the things he promised to, or tried to do the things he’s promised to.” Trump’s most notable achievement, according to Mr Mellon, was “in trade and righting the balance between our country and the rest of the world, especially China”.

In 2012, Mr Mellon donated $1m to a group dedicated to finding the remains and aircraft of Amelia Earhart, a famous American aviator who vanished while flying over the Pacific in 1937.

Ric Gillespie, the executive director of the group – International Group for Historic Aircraft Recovery – later told US media outlet NOTUS that Mr Mellon joined them on a fruitless expedition to search for the plane.

“We didn’t find anything,” Mr Gillespie said. “But he wasn’t complaining at anything, he was just along for the ride and he didn’t involve himself very much. He spent most of his time sitting on the ship, reading.”

A year later, Mr Mellon filed a lawsuit against the organisation in which he claimed the plane already had been discovered before he gave them the money. A judge ruled against him, however, noting that Mr Mellon’s own experts were unable to prove the plane had been found.