Story highlights Donald Trump Jr promoted a long-debunked, far-right conspiracy theory on Thursday by sharing a tweet that linked former President Bill Clinton's firing of an FBI director to the death of his then-aide, Vince Foster.

Several investigations have ruled Foster's 1993 death a suicide.

(CNN) Donald Trump Jr promoted a long-debunked, far-right conspiracy theory on Thursday by sharing a tweet that linked former President Bill Clinton's firing of an FBI director to the death of his then-aide, Vince Foster.

In an apparent effort to defend his father's firing of FBI Director James Comey, Trump Jr. retweeted user @StockMonsterUSA, who wrote, "President Clinton fired his FBI director on July 19th, 1993, The Day before Vince Foster was found dead in Marcy Park." The tweet included a picture of Foster with the Clintons.

Several investigations have ruled Foster's 1993 death a suicide. However, conspiracy theories spread by the far-right linking the Clintons to Foster's death still persist to this day.

During the campaign, then-candidate Donald Trump alluded to these theories in an interview with the Washington Post and referred to Foster's death as "very fishy"

Trump Jr. didn't immediately respond to an email seeking comment.