Barr Plans to Return to Justice Dept. After Negative Coronavirus Test Results

After Mr. Trump revealed early on Friday that he had tested positive for the virus, Mr. Barr took a rapid test each day and took an additional diagnostic test called a PCR test, and made their results public. Through the weekend, his tests came back negative, Ms. Kupec said.

Mr. Barr also decided to reduce his schedule to one meeting on Friday and to self-quarantine at home over the weekend, she said.

Ms. Kupec said on Monday that Mr. Barr had not had any contact with Mr. Trump for nine days, when both men attended a reception at the White House for the president’s Supreme Court nominee, Judge Amy Coney Barrett.

Several Republican leaders and others who attended the reception have since learned they have the virus, including Mr. Trump; the first lady, Melania Trump; Senators Mike Lee of Utah and Thom Tillis of North Carolina; John I. Jenkins, the president of the University of Notre Dame; Chris Christie, the former governor of New Jersey; and Kellyanne Conway, a former counselor to the president.

Mr. Barr was photographed standing in proximity to Ms. Conway at the reception, during which neither person wore a mask.

According to the Justice Department’s coronavirus guidance, “individuals ill with, or exposed to individuals with Covid-19, should self-quarantine for 14 days.”

The event for Judge Barrett also seemed to have violated Washington’s guidance for gatherings during the pandemic. More than 150 people attended; Mayor Muriel E. Bowser has stipulated that no private gatherings should exceed 50 people and that attendees must wear masks, particularly in spaces where they cannot remain six feet apart.