"The Special Council's reasons remain unknown," Howell wrote. “The reason is not that the individuals were insignificant for the investigation. On the contrary, both of the non-witnessing individuals mentioned in paragraph four were in key events reviewed in the Mueller Report. Evaluating these choices of specialist advice is a matter for others. "
Trump Jr. was present at the now-famous Trump Tower meeting in June 2016, where Trump campaign officials met with the Russians. Prior to that meeting, he also received an "dirt" email from Democratic presidential candidate Hillary Clinton.
"If that's what you say, I love it," Trump Jr. replied.
A Trump Jr. attorney, Alan Futerfas, did not immediately respond to a request for comment on the affirmation that his client never testified.
The Mueller report says Trump Jr. declined a voluntary interview, but several lines following this statement have disappeared.
Attorneys for other witnesses in the probe have said they believe Trump Jr.'s lawyers informed prosecutors that he would assert his Fifth Amendment right to self-incrimination if called to the grand jury and that Mueller's team chose not to force his testimony by asking a judge to grant him immunity.
In April, prior to the publication of the report, one of the president's personal lawyers silenced the speech that Trump Jr. was exercising his constitutional right to remain silent.
"I can say that I have no knowledge that anyone took fifth," Rudy Giuliani said at the time.