The timeline of events surrounding Hunter Biden’s appointment to the board of Burisma Holdings, a Ukrainian natural gas company, undercuts Joe Biden’s newest defense about not being made aware that his son’s overseas dealings could pose a conflict of interest.

The former vice president, who has repeatedly changed his story on how much he knew about his youngest son’s ties to Burisma, claimed over the weekend that White House staff never brought the subject to his attention. In particular, Joe Biden asserted he was never warned that his son’s work with Burisma and his own position overseeing Obama administration policy in Ukraine could pose a conflict.

“Nobody warned me about a potential conflict of interest,” the former vice president told NPR in an extensive interview. “Nobody warned me about that.”

When pressed with the fact that a top U.S. diplomat to Ukraine had attempted to raise the matter in 2015, but was rebuffed by the former vice president’s staff, Joe Biden suggested such a result occurred because his oldest son, Beau Biden, was losing his battle with brain cancer at the time.

“Well, my son was dying, so I guess that’s why he said it, because my son was on his deathbed,” he said. “But that, that’s not the reason why — they should have told me.”

The former vice president’s plea of ignorance comes after he claimed in September to have never spoken about Burisma with his youngest son, even though Hunter Biden has stated otherwise. It also stands in direct contradiction to claims made by one of his top White House advisers.

More troubling, however, is that Joe Biden’s newfound defense does not fit with the official timeline of events.

Hunter Biden joined Burisma’s board of directors in May 2014, alongside his longtime business partner Devon Archer. Officially, Hunter Biden was tapped for the position, which paid as much as $83,000-per-month, because of his experience in “transparency, corporate governance” and international expansion.

The appointment quickly set off alarm bells in Washington, D.C. and Europe. As Peter Schweizer detailed in his book, Secret Empires: How the American Political Class Hides Corruption and Enriches Family and Friends, Hunter Biden received the Burisma role despite having no background in the energy industry or Ukraine. His lack of experience, coupled with the fact his father had just been made the Obama administration’s point man on Ukraine, immediately raised questions from ethics watchdogs.

Adding to concerns was that Hunter Biden joined the company at a time when it was actively courting western leaders to prevent scrutiny of its practices. The same month as the appointment, Mykola Zlochevsky, Burisma’s founder, had his assets frozen in the United Kingdom on suspicion of money laundering. A Ukrainian official with ties to Zlochevsky admitted in October the only reason Hunter Biden secured his position with Burisma was to “protect” the company from foreign scrutiny.

Given the murky history and Hunter Biden’s lack of qualifications, it is no surprise the matter quickly generated attention. Evidently, one of the people most worried about the appointment was Christopher Heinz, former Secretary of State John Kerry’s stepson who at the time co-owned an investment firm with Hunter Biden and Archer. Only hours after the announcement was made, Heinz rushed to play damage control with State Department officials, as indicated by official emails obtained by the Washington Examiner.

“Apparently Devon and Hunter both joined the board of Burisma and a press release went out today,” Heinz emailed two of his stepfather’s top aides. “I cant speak why they decided to, but there was no investment by our firm in their company.”

It is unclear what came of that correspondence or if it played any role in the official line taken by the Obama-era White House on the matter.

As the Washington Free Beacon previously noted, on the day of the appointment White House press secretary Jay Carney and State Department spokesperson Jen Psaki fielded questions about Hunter Biden’s role with Burisma. At the time, Carney and Psaki ducked the questions, telling the media Hunter Biden was a “private citizen,” and referring the matter to then-Vice President Joe Biden’s office.

A review of statements issued by the former vice president’s office seems to indicate no public comment was made in days following the appointment. It is unlikely that the either the White House or the Kerry-led State Dept. would have issued initial statements without coordinating with then-vice president or his staff.

Furthermore, complicating Joe Biden’s claims to have been too preoccupied with his oldest son’s battle with cancer at the time of the appointment, is that Beau Biden’s health seemed to be improving by May 2014. Beau Biden, who served as the attorney general of Delaware from 2007 to 2015, was first diagnosed with cancer in August 2013 after suffering from “disorientation and weakness.”

By some accounts, the eldest Biden son was in remission by the early 2014, but still dealing with the effects of the disease. The notion seemed corroborated by Beau Biden, himself, when he announced his intent to run for governor of Delaware in April 2014—less than a month before Hunter Biden signed up with Burisma.

Although Joe Biden has not openly discussed the progression of his son’s battle with cancer, the former vice president wrote in his recent memoir, Promise Me, Dad, that Beau’s illness became substantially worse in August 2014. After the summer of 2014, Beau Biden’s health steadily deteriorated, with him tragically losing his battle with cancer in May 2015.

It was around the time of Beau’s passing that George Kent, who was then-U.S. Deputy Chief of Mission to Ukraine, reached out to the former vice president’s office to raise his concerns about Hunter Biden’s work with Burisma. Kent, who is now a deputy assistant secretary of state, told the House Intelligence Committee in November he felt compelled to speak out because he suspected Zlochevsky was guily of bribing Ukrainian officials.

Kent told lawmakers as part of the impeachment inquiry:

After, I became aware that Hunter Biden was on the board of Burisma. Soon after that in a briefing call with … office of the vice president in February 2015, I raised my concern that Hunter Biden’s status as a board member could create the perception of a conflict of interest.

Kent testified that Joe Biden’s staff dismissed the concerns, claiming the then-vice president lacked the “bandwith” to address the issue because of his eldest son’s illness.

Joe Biden still seemed to be unable to address the issue more than six months after Beau’s death. Amos Hochstein, once a close adviser to the former vice president, told The New Yorker in July that he broached the subject of Burisma with Joe Biden in December 2015:

Joe Biden prepared to return to Ukraine, his aides braced for renewed scrutiny of Hunter’s relationship with Burisma. Amos Hochstein, the Obama Administration’s special envoy for energy policy, raised the matter with Biden, but did not go so far as to recommend that Hunter leave the board.

Joe Biden, though, claims that conversation never took place.