Who is Devon Archer? Former Hunter Biden business partner worked with him in Ukraine, China

Republicans hope Devon Archer can help them open up fresh lanes of inquiry in their ongoing investigation of President Joe Biden's family -- and they promoted his appearance before the House Oversight Committee on Monday, for closed-door testimony, as a major development in a probe that has thus far been heavy on accusations but light on evidence.

So, who is Devon Archer?

In the long-running drama that is Hunter Biden's overseas business dealings, Archer is an important recurring character whose relationships in Ukraine and China precipitated many of the younger Biden's ill-fated endeavors in both countries.

The two first met through a mutual connection -- Christopher Heinz, an heir to the food company and John Kerry's stepson.

Archer and Heinz had been friends at Yale. In his memoir, "Beautiful Things," Hunter Biden called Archer a "self-made, supermotivated former college lacrosse player with a disarming charm."

In 2009, Hunter Biden and Archer co-founded Rosemont Seneca Partners, an advisory firm that provided "alternative investment opportunities and market guidance that seek to afford an absolute return through our global economic reach and expertise," according to the group's archived website.

In Ukraine, it was Archer who initially "raised my name for a possible board seat" at Burisma, a Ukrainian oil and gas conglomerate, Hunter Biden wrote in his memoir.

ABC News has reported that Hunter Biden and Archer, who also secured a seat for himself, raked in $166,666 payments each month for their work with the firm.

Archer also brokered deals for Rosemont Seneca in China, including its relationship with Jonathan Li -- a Chinese businessman whom Hunter Biden introduced to his father, then-Vice President Joe Biden, during a trip to Beijing in 2013, Hunter Biden wrote in his memoir.

In a 2019 interview with ABC News, Hunter Biden defended that brief meeting -- which sparked criticism from Republicans when it became public.

"Whether I'm in New York, or whether I'm in Washington, D.C. … [and] a friend and a business associate is in the hotel, and my dad's staying there -- is it inappropriate for me to have coffee with him?" Hunter Biden asked rhetorically.

Archer's relationship with President Biden has also attracted scrutiny from Republicans. A GOP-led Senate panel found in 2020 that Archer met with the elder Biden at the White House in 2014 shortly before he departed for a trip to Ukraine. (Archer and Hunter Biden told The New Yorker that the visit was arranged for Archer's son, who at the time was working on a grade school project on the White House.)

A photo of Joe Biden golfing with his son and Archer in 2014 has prompted accusations that the then-vice president was more involved in Hunter Biden's business endeavors than either party has led on.

Asked about that photo on the campaign trail in late 2019, Joe Biden bristled at the accusation and said "it's not a conflict."

Archer arrived on Capitol Hill on Monday with his own nagging legal travails. He was convicted on federal tax charges in 2018 as part of a conspiracy to defraud a Native American tribe. The conviction was overturned, reinstated and appealed. Archer is expected to report to prison in the coming months.

After several hours, Archer finished his closed-door interview on Capitol Hill on Monday and ignored questions from reporters as he left with his lawyer.

In a statement afterward to ABC News, an attorney for Archer said he had answered the committee's questions "honestly and completely."

"We are aware that all sides are claiming victory following Mr. Archer's voluntary interview today. But all Devon Archer did was exactly what we said he would: show up and answer the questions put to him honestly and completely," Matthew L. Schwartz said. "Mr. Archer shared the truth with the Committee, and we will leave to them and others to decide what to do with it."

ABC News' Lauren Peller contributed to this report.