Donald Trump Jr.Don TrumpHow Trump uses fundraising emails to remain undisputed leader of the GOP Donald Trump Jr. joins Cameo Book claims Trump family members were 'inappropriately' close with Secret Service agents MORE took to Twitter on Sunday to troll House Intelligence Committee Chairman Adam SchiffAdam Bennett SchiffHouse passes bill to compensate 'Havana syndrome' victims House Democrats unveil legislation to curtail presidential power Overnight Hillicon Valley — Hacking goes global MORE (D-Calif.) hours after Attorney General William Barr delivered a summary of special counsel Robert MuellerRobert (Bob) MuellerSenate Democrats urge Garland not to fight court order to release Trump obstruction memo Why a special counsel is guaranteed if Biden chooses Yates, Cuomo or Jones as AG Barr taps attorney investigating Russia probe origins as special counsel MORE’s investigation to Congress.

As lawmakers from both sides of the aisle reacted following Barr’s summary of Mueller’s lengthy investigation into collusion between the Trump campaign and Russia to interfere in the 2016 election, Trump Jr. knocked Schiff for remaining quiet.

“Has anyone heard from slimy Adam #fullofschiff Schiff today?” Trump Jr. wrote in a post on Twitter Sunday evening. “I mean it must be embarrassing to have have spent the last 2 years as the leader of the tinfoil hat brigade and have it all come crashing down so quick.”

Trump Jr. borrowed the “full of Schiff” reference from his father. President TrumpDonald TrumpUN meeting with US, France canceled over scheduling issue Trump sues NYT, Mary Trump over story on tax history McConnell, Shelby offer government funding bill without debt ceiling MORE has consistently ripped the California lawmaker, who is leading a congressional investigation into Trump.

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Trump’s son added that he is “legitimately concerned for his mental state,” referring to Schiff.

On Sunday morning, before Barr delivered his letter to Congress, Schiff said Congress would have to consider impeaching Trump if Mueller’s report found “overwhelming evidence of criminality” on Trump's part.

According to Barr’s letter, which summarized the conclusions from Mueller’s investigation, there was no evidence of collusion between the Trump campaign and Russia to interfere in the 2016 election.

The letter says that Mueller did not make a conclusion as to whether Trump obstructed justice in the investigation of Russia's election interference, though Barr and Deputy Attorney General Rod RosensteinRod RosensteinWashington still needs more transparency House Judiciary to probe DOJ's seizure of data from lawmakers, journalists The Hill's Morning Report - Biden-Putin meeting to dominate the week MORE decided they would not pursue an obstruction of justice charge against Trump.