Hunter Biden and his investment firm partner, Chris Heinz, split up after Biden decided to join the board of a gas company owned by a Ukrainian oligarch.

Heinz, who is former Secretary of State John Kerry's stepson, and Biden - son of former Vice President Joe Biden - had partnered up in 2009 to form the Rosemont Seneca investment firm, but parted ways in 2014.

According to a Washington Post report, Heinz ended his working relationship with Biden later that year, after Biden took a board position on Burisma Holdings, which was owned by businessman Mykola Zlochevsky, Ukraine's former Minister of Ecology and Natural Resources.

Chris Heinz (left) parted ways with investment firm partner Hunter Biden (right) in 2014 after Biden accepted a board position on Burisma Holdings, a company run by a Ukrainian oligarch

Burisma Holdings was owned by businessman Mykola Zlochevsky, Ukraine's former Minister of Ecology and Natural Resources

Biden - whose father was Vice President at the time and was in the midst of helping to eliminate corruption in the Ukraine - supposedly joined the board in 2013 after another one of Rosemont Seneca's partners, Devon Archer, joined Burisma Holdings' board.

Biden was said to have joined energy company Bursima because former President of Poland, Aleksander Kwasniewski, also a Burisma board member, urged him to do so.

Biden supposedly also believed that helping the Ukraine to achieve energy independence would help protect the company from Russian President Vladimir Putin.

Heinz's decision to end his business relationship with both Biden and Archer was said to be due to concerns about corruption in Ukraine and appearances.

Heinz's spokesperson told the newspaper that 'the lack of judgment in this matter was a major catalyst for Mr. Heinz ending his business relationships with Mr. Archer and Mr. Biden.'

Around the time when Hunter Biden's father, former Vice President, was working to end corruption in the Ukraine. Hunter (left) and Joe (right) are pictured in April 2016

Heinz (second from right) is pictured with stepfather John Kerry, the former Secretary of State

Biden's role at the Ukrainian energy company has made headlines after a whistleblower's complaint surfaced, in which Trump (left) supposedly asked Ukraine president Volodymyr Zelensky (right) to investigate Hunter and his father

Biden went on to serve on the Burisma board from 2013 to April 2014, when his term expired and he left the company, according to Reuters.

In 2014 - the year Heinz parted ways with Biden and Archer - Ukrainian prosecutors opened a criminal investigation into Burisma on suspected tax violations.

In March 2016, Vice President Joe Biden took credit for pushing out getting Ukraine’s prosecutor general, Viktor Shokin, fired after telling the Ukrainian government that the Obama administration's $1billion in loan guarantees would be withheld unless the Ukraine started removing officials who were seen as trying to block anti-corruption efforts in the country, according to Vox.

Shokin - who many Western officials also wanted out - was seen as being one of the people who was an impediment in the investigation into Burisma.

Two years later, the court found that there was no evidence of criminal wrongdoing by owner Zlochevsky and he was taken off the 'wanted list.'

Biden's position on Burisma, however, became headline news because of its role in the whistleblower's complaint, which said that President Trump had asked Ukrainian President Volodymyr to investigate Biden and his father - who is running as a 2020 Democratic presidential candidate.

According to the whistleblower, the transcript of the call was put on a top secret server and access to the transcript was restricted, even though no classified information had been discussed.

The complaint, which became public last week, led House Speaker Nancy Pelosi to finally launch an impeachment inquiry into Trump.​

Trump and his camp have been spreading a conspiracy theory which claims that Joe Biden's efforts on getting Shokin removed were on behalf of protecting Hunter Biden.

A spokesperson for Joe Biden's campaign told the Washington Post that: 'Joe Biden proudly fought for reform in Ukraine and his achievement of a goal the U.S., EU, IMF, and entire Ukrainian anti-corruption community all strongly supported was a profound victory for good government there.'