Members of special counsel Robert Mueller's team are looking at President Trump's oldest son, Donald Trump Jr., to determine the intent behind his attendance at a June 2016 meeting at Trump Tower with a Russian lawyer, according to a report.

A source familiar with the investigation into potential ties between Trump campaign officials and Russians told BuzzFeed that federal prosecutors are working to figure out what information Trump Jr. was provided during the meeting. Federal prosecutors are also examining Trump Jr.'s own comments about the June 2016 gathering.

Trump Jr. attended the meeting, along with the president's son-in-law Jared Kushner and then-Trump campaign chairman Paul Manafort, with Natalia Veselnitskaya, the Russian lawyer, after he was promised damaging information on Hillary Clinton.

Trump Jr. has said he didn't receive any useful information on Clinton and said the meeting lasted only for a short time. Instead, the conversation shifted to the Magnitsky Act, a 2012 law that punished Russian human rights abusers, and the issue of American adoptions of Russian children.

It is a violation of federal election law for a presidential campaign to request or accept anything of value from a foreign national. Democrats have insisted that campaign dirt on Clinton would qualify as something of value, but others disagree, and it could be a question that has to be tested in court.

White House counsel Ty Cobb told BuzzFeed, "I don't know anything about that in the sense of what their motivations or interest are. I wouldn't comment on it."

According to BuzzFeed, the federal prosecutors working on Mueller's team are focused on Trump Jr.'s mindset when he met with Veselnitskaya on June 9, 2016. They also want more details on the information about Clinton offered to the president's son.

Trump Jr. discussed the information offered to him with Fox News host Sean Hannity last month.

"It was this, you know, hey, some DNC donors may have done something and Russia and they didn't pay taxes. I was like, what does this have to do with anything?" Trump Jr. told Hannity of the meeting.

But two sources told BuzzFeed the information offered was a "complicated set of allegations" about donations to the Clinton Global Initiative from Ziff Brothers Investments.

The investment fund was allegedly linked to a man named William Browder, who invested in Russia but pushed for passage of the Magnitsky Act, the 2012 law that Veselnitskaya discussed with Trump Jr. at the meeting.

BuzzFeed reported prosecutors aren't focused on the information, but rather Trump Jr.'s thinking when he received it.