Washington (CNN) Donald Trump Jr. says in his forthcoming book that he "almost felt bad" for Robert Mueller, mocking the former FBI director and special counsel's July testimony before Congress, according to The New York Times .

"If it weren't for the fact that I was probably number two on the guy's kill list for years, I might have," writes Trump Jr. in his book "Triggered," according to excerpts obtained by the Times and published Friday. CNN has not obtained a copy of the book set to release next week.

According to a description of the book , the President's eldest son "will expose all the tricks that the left uses to smear conservatives and push them out of the public square." The Times reports Trump Jr. writes that Democrats put Mueller before Congress "so he could stutter and babble his way through five hours of testimony."

CNN has reached out to a spokesman for Mueller for comment.

Trump Jr. was a focus of the special counsel investigation into his father's presidential campaign and connections with Russia for his role in a June 2016 meeting at Trump Tower with a Russian lawyer for "dirt" on Hillary Clinton , his father's 2016 presidential opponent.

Mueller concluded his investigation in late March and the Justice Department released a redacted version of his near 450-page report in mid-April. In his July testimony, Mueller mostly stuck to the report, but his performance was halting and shaky

The special counsel did not find evidence to charge any Americans with conspiring with the Russians, though prosecutors have alleged that Russian government actors broke US law as they attempted to help Donald Trump in the 2016 election. Mueller found several instances when associates of Trump had been in touch with Russians in 2016, and documented how campaign officials had realized that then-candidate Trump could benefit from the Russians' efforts.

The special counsel's investigation into possible obstruction of justice also could not clear Trump.

"While this report does not conclude that the President committed a crime, it also does not exonerate him," the report said.

In a 2018 interview with ABC News , Trump Jr. said the investigation was "very difficult" for him personally, but said he was not concerned about legal exposure "because I know what I did, and I'm not worried about any of that."