Robert Patterson was publicly announced as the Drug Enforcement Administration's acting administrator Tuesday evening, ending uncertainty about who was leading the large counternarcotics agency.

Patterson was formally appointed by Attorney General Jeff Sessions on Monday.

It's unclear how long Patterson, who has worked at the DEA since 1988, will serve in the role. But reports that the Justice Department is considering outside candidates suggest he may be a temporary leader.

The previous head of the DEA, acting administrator Chuck Rosenberg, abruptly stepped down Sunday, giving only five days notice of his departure. Rosenberg, a former U.S. attorney and chief of staff to fired FBI Director James Comey, told employees in August to ignore remarks from President Trump that he said "condoned police brutality."

Following Rosenberg's departure, it was unclear on Monday and for most of Tuesday who was in charge at DEA.

A "leadership" page on the agency's site replaced a biography of Rosenberg for one of Patterson, DEA's principal deputy administrator since November, but DEA officials said they were waiting for official word of a White House decision to appoint an acting administrator.

DEA spokeswoman Mary Brandenberger said Monday the lapse did not affect day-to-day operations, but also said "I honestly don't know" who would be making decisions. On Tuesday, Brandenberger objected to being quoted saying so, but refused to say if she knew who was in charge.

The DEA has a leading role in stopping the illegal drug trade, but has other roles, too, including classifying drugs into restrictive categories based on danger and medical use, and controlling the research and scientific supply of banned substances.

The agency's roles often put it at the center of the debate over marijuana policy. Some policy advocates believe the DEA's leader will have a major role shaping the Justice Department's ongoing review of Obama-era policy allowing for state-regulated recreational sales in violation of federal law.

The appointment of Patterson to be acting administrator comes after reports that New Jersey State Police Superintendent Rick Fuentes was contacted regarding his interest in the position. Others also were said to have been in touch with the Justice Department regarding the job

Acting administrators sometimes are long-serving. Rosenberg served more than two years as an acting administrator, and his predecessor Michele Leonhart went more than three years without Senate confirmation.

The Tuesday evening release announcing Patterson's appointment says: "The Department of Justice has designated Robert W. Patterson as the Drug Enforcement Administration acting administrator," but it's unclear if the phrasing suggests anything regarding the White House's involvement.

Patterson began work at the DEA in New York in 1988. He later held positions in Florida before taking top jobs at the central DEA, including as acting special agent in charge of the agency's Special Operations Division.

The press release announcing his appointment says in his time ahead of the Special Operations Division he "oversaw classified programs, and communication exploitation tools, in support of field operations."

Among the efforts Patterson oversaw was the mass interception of U.S. phone call metadata for international calls placed by people inside the U.S. to certain other countries, including Iran and an unknown number of others.

Patterson, 8 years into the position, revealed details of the effort in 2015 in a court declaration that was later released with redactions, saying the program was ended in September 2013, after whistleblower Edward Snowden triggered a broad debate on mass surveillance.

Patterson said the program monitored contacts with countries "determined to have a demonstrated nexus to international drug trafficking and related criminal activities." It's unclear what his exact role was in establishing, maintaining or deciding to end the controversial surveillance program.

This article was updated to note that the order appointing Patterson acting administration was signed on Monday.