President Trump on Wednesday pardoned a Florida health care executive whose mother played a role in trying to expose the contents of Ashley Biden’s diary.

The pardon of the executive, Paul Walczak, was signed privately and posted on the Justice Department’s website on Friday. It came less than two weeks after he was sentenced to 18 months in prison and ordered to pay nearly $4.4 million in restitution, for tax crimes that prosecutors said were used to finance a lavish lifestyle, including the purchase of a yacht.

Mr. Walczak’s mother, Elizabeth Fago, who was also involved in the health care industry in Florida, is a longtime Republican donor and fund-raiser who played a role in a surreptitious effort to help Mr. Trump by undermining Joseph R. Biden Jr. in the 2020 presidential election.

During the campaign, Ms. Fago was contacted by a man who was in possession of a diary kept by Mr. Biden’s daughter, Ashley, as she recovered from addiction, The New York Times previously reported.

When first told of the diary, Ms. Fago said she thought it would help Mr. Trump’s chances of winning the election if it was made public, two people familiar with the matter later told The Times. The man, Robert Kurlander, circulated the diary at a fund-raiser at Ms. Fago’s house in Jupiter, Fla., in September 2020.

Ms. Fago’s daughter passed along a tip about the diary to Project Veritas, a conservative group that had become a favorite of Mr. Trump’s. Project Veritas later paid $40,000 to Mr. Kurlander and an associate, Aimee Harris, for the diary.