Washington, July 29 (RHC)-- The U.S. special counsel has called on White House officials to preserve any document relating to a last year meeting -- attended by President Donald Trump’s eldest son, son-in-law and a Russian lawyer -- to determine if the president knew about the gathering.  Special counsel Robert Mueller sent a request to White House staff and called to save "any subjects discussed in the course of the June 2016 meeting" and also "any decisions made regarding the recent disclosures about the June 2016 meeting," CNN quoted an unnamed source who said has seen the letter.

“Information concerning the June 2016 meeting between Donald J Trump Jr and Natalia Veselnitskaya is relevant to the investigation," read the letter.

It was recently revealed that Trump’s son, Donald Trump Jr., Trump's son-in-law, Jared Kushner, and then-campaign chairman Paul Manafort sat down in a meeting with Russian attorney Natalia Veselnitskaya at Trump Tower back then.  Trump’s son said he had been promised damaging information about his father’s opponent, Democratic nominee Hillary Clinton.  He, however, claimed that he did not receive the information he was promised.

The meeting is now widely considered as part of efforts by Russia to collude with the Trump’s campaign in an effort to change the outcome of the November 8 presidential election; accusations that Russia has firmly denied.  Mueller, who was appointed by the justice department in May to investigate the allegations, is now looking for any indication that Trump knew about the meeting and might have suggested topics for discussion, according to the source. Muller is also investigating to know whether the president was briefed on the meeting afterward, the source said.

Document requests sent by Muller could include text messages, voicemails, e-mails, notes or records.  The ongoing investigation has infuriated Trump since he has been informed about the legal questions that he and his family could face.  He has even escalated efforts to discredit the special counsel, according to reports.

The New York Times reported earlier this week that the president’s lawyers were looking for conflicts of interest among members of Mueller’s team to discredit the probe or even get Mueller fired.  The Washington Post also reported that Trump has asked his advisers about his power to grant pardon to his family members, his aids and even himself in connection with the investigation.

Any use of the pardon power to end or obstruct the probe would be considered as an abuse of power and would provide legitimate grounds for his impeachment.