The meeting took place in June 2016 at Trump Tower, and included a total of eight people, also including then Trump campaign chairman Paul Manafort and the President's son-in-law Jared Kushner and a Russian American lobbyist. When its existence was revealed earlier this year along with indications that Trump Jr. accepted the meeting because he was told he would learn dirt about Clinton, the revelation sparked intense interest given allegations of collusion between the Trump campaign and a Russian election meddling effort.
"To the extent they had information concerning the fitness, character or qualifications of a presidential candidate, I believed that I should at least hear them out," Trump Jr. said in an opening statement to staffers, according to the Times.
He also stated that he had always intended to consult a lawyer before using any information.
"Depending on what, if any, information they had, I could then consult with counsel to make an informed decision as to whether to give it further consideration," he said in the statement.
Trump Jr.'s reported statement contrasted with his initial comments that he made when the meeting was first revealed, in which he said the focus was restricted to a discussion about a frozen Russia-US adoption program. That explanation soon yielded to a succession of reworded statements about why he met the lawyer that cemented impressions that Trump Jr. was not disclosing everything about the encounter.
Thursday's meeting before the Senate staffers was attended by several senators, including Democrat Dick Durbin, who told reporters that Trump Jr. appeared to be behaving cooperatively.
The cloud formed by claims that members of Trump's White House campaign colluded with a Russian election meddling operation has been consumed in recent days by the murderous winds and tides of multiple Atlantic hurricanes.
But with Congress back at work after the summer recess, the pace of its probes into the Russia effort is accelerating, even as Justice Department Special Counsel Robert Mueller methodically plods ahead with his own investigation.
Trump Jr.'s appearance could be the prelude for other full-scale public hearings focusing on his role as an unofficial campaign aide to his father.
The Senate intelligence committee has been the main panel in the chamber looking into the Russia matter, though the judiciary committee under GOP Chairman Chuck Grassley has intensified its focus in recent months.
Sen. Dianne Feinstein told CNN Wednesday there would be a public hearing
with the President's son "at an appropriate time" and that he would be subpoenaed if necessary.
Trump Jr. became a central figure in the Russia drama after it emerged that he had attended a meeting in June 2016 with a Russian lawyer
with connections to the Kremlin after being promised information damaging to Hillary Clinton.
Senate intelligence committee chairman Richard Burr, and the panel's top Democrat, Mark Warner, privately met Wednesday and said that they'd like to talk to other attendees of the Trump Tower meeting before meeting with Trump Jr., which could push back the panel's plans to hear from the President's son this month.
Following intense interest in the meeting at Trump Tower, the President's son released emails that show he was told by a facilitator, publicist Rob Goldstone, that the encounter was part of "Russia and its government's support for Mr Trump."
Committee staffers are also likely to be interested in reports by The Washington Post that
the President was involved in May in drafting a statement about the meeting on behalf of his son about the meeting, while flying home from the G20 summit in Germany.
The White House has said that Trump was involved in the drafting of an initial statement, but only in his capacity as a father and that there were no inaccuracies in the document.
But the reports immediately tweaked suspicions among Trump critics who believe the President has consistently sought to shut down investigations into the Russia drama, including with his firing of FBI Director James Comey
Jens David Ohlin, Vice Dean of Cornell Law School, who has been closely following the Russia story, said that investigators were finally beginning to get a handle on the scope of the probes, but cautioned that they were likely still a long way from ending.
"These are investigations that have multiple tentacles," he said, adding that the "perimeter is starting to get defined and what investigators are going to start doing now is filling in that empty space between that perimeter."
Mueller also appears to be investigating the meeting between Donald Trump Jr. and the Russian lawyer. He asked the White House to preserve any documents related to the encounter. CNN has identified eight people at the talks, including then Manafort, Kushner and Rinat Akhmetshin
, a Russian American lobbyist.
CNN has also reported that some White House aides involved in the hurried efforts to explain the Trump Tower meeting may have exposed themselves to legal scrutiny by the special counsel.
Trump Jr. is also likely to be of interest to investigators interested in the extent of the Trump family's investments and exposure in Russia before the campaign.
The President has repeatedly denied having any business interests in Russia.
"For the record, I have ZERO investments in Russia," he tweeted for example in July 2016, and then reiterated that point again at a news conference the following day, telling reporters "I have nothing to do with Russia."
But the appearance by Donald Trump Jr. on Capitol Hill is not the only significant, recent development in the Russia probes -- related to the President's past business ventures.
Last week, it emerged that Trump's attorney reached out to the Kremlin for help in building a Trump Tower in Moscow
well into Trump's presidential campaign.
Trump's personal attorney, Michael Cohen, has told CNN that he emailed a top aide of Russian President Vladimir Putin, Kremlin spokesman Dmitry Peskov, about the proposed building, saying the message "went unanswered" and "was solely regarding a real estate deal and nothing more." Cohen also said he contacted Peskov after it was suggested that the proposal would require approval by the Russian government, but that approval was never provided.
Cohen added that he discussed the proposal with Trump three times, saying he "never considered asking Mr. Trump to travel to Russia in connection with this proposal" and did not brief on him on his decision to terminate the development.
The top Democrat on the House Intelligence Committee, Adam Schiff told CNN's Wolf Blitzer on Wednesday that the disclosures raised "additional concerns:"
"Now we know that the Trump organization was pursuing business in Russia, business that would effectively have to be approved by Putin.
"At the same time, the campaign was taking a pro-Russia, pro-Putin policy. Was this being guided by their financial interests?
"And why did the President make false statements about his financial interests in doing business in Russia at a time when he was pursuing that?" he said.
Much is unknown about Mueller's probe. But the latest developments suggest the special counsel is mounting a serious investigation into whether Trump obstructed justice that could have grave implications for his presidency.
While much of America was fixated on the aftermath of Hurricane Harvey late last week, The New York Times reported that Mueller had a draft of a letter that explains reasons why he planned to fire Comey
The contents of the letter have not been revealed. But the paper said it met with opposition from White House counsel Don McGahn, who saw its contents as "problematic."
And in yet another development, The Wall Street Journal first reported that Trump's lawyers filed memos with Mueller arguing that the President was simply exercising constitutional powers in firing Comey.