Sen. Richard Burr, R-N.C., has resigned his position as chairman of the Senate Intelligence Committee on Thursday after the FBI served a search warrant for his cellphone as part of an ongoing insider-trading investigation tied to the coronavirus pandemic. Burr said the resignation was temporary.

Senate Majority Leader Mitch McConnell announced the move, saying he and Burr had agreed that it was in the committee’s best interests.

Clinically Studied Pain Relief Formula Used by Surgeons, Now Available to the Public [sponored]

FBI officials showed up at Burr’s home with the warrant on Wednesday, two people familiar with the investigation said Thursday, marking a significant escalation into the Justice Department’s investigation into whether Burr broke the law with a well-timed sale of stocks before the coronavirus caused markets to plummet.

The search warrant was served on Burr’s lawyers, and FBI agents raided Burr’s home in the Washington area to retrieve the cellphone, a senior Justice Department official said. The decision to obtain the warrant, which must be authorized by a judge, was approved at the highest levels of the department, the official said.

The official could not discuss the ongoing investigation publicly and spoke on the condition of anonymity.

The Justice Department declined to comment. Burr’s attorney said in a statement last month that the law is clear that any senator can participate in stock market trading based on public information “as Sen. Burr did.” The attorney, Alice Fisher, said that Burr welcomed a review of the stock sales, “which will establish that his actions were appropriate.”

Burr has denied wrongdoing but has also requested an ethics review of the stock sales.

Burr is an amiable member of the Senate, and his quick call for an ethics investigation and willingness to cooperate with authorities appears to have bought him some goodwill among colleagues tapping down immediate calls for him to step aside.

Senate records show that Burr and his wife sold between roughly $600,000 and $1.7 million in more than 30 transactions in late January and mid-February, just before the market began to nosedive and government health officials began to sound alarms about the virus. Several of the stocks were in companies that own hotels.

Burr has acknowledged selling the stocks because of the coronavirus but said he relied “solely on public news reports,” specifically CNBC’s daily health and science reporting out of Asia, to make the financial decisions.

Burr was not the only lawmaker to sell off stocks before the market slide.

Sen. Kelly Loeffler, a new senator from Georgia up for reelection this year, sold hundreds of thousands of dollars worth of stock in late January and February, as senators began to get briefings on the virus, according to records.

So did fellow Georgia Sen. David Perdue, another Republican lawmaker running for reelection, and also Republican Sen. James Inhofe of Oklahoma, and Democratic Sen. Dianne Feinstein of California

Senators did receive a closed-door briefing on the virus on Jan. 24, which was public knowledge. A separate briefing was held Feb. 12 by the Senate Health, Education, Labor, and Pensions Committee, which Burr is a member of. It’s unclear if he attended either session.

Burr’s six-year term ends in 2023 and he does not plan to run for reelection.

He was first elected to the Senate in 2004 and chaired the Senate Intelligence Committee as the panel conducted its own investigation into Russian election interference in the 2016 presidential election. The committee recently issued a report supporting the intelligence community’s conclusion that Russia had interfered on Trump’s behalf.

GOP senator resigns position after FBI search warrant

READ MORE: Investigators probe Dianne Feinstein’s coronavirus “cash grab”