Attorney General Merrick Garland on Friday told leaders of the nation’s largest law-enforcement organizations that an investigation into the Minneapolis Police Department will be the first—but not last—broad civil-rights probe of a local agency that the Justice Department intends to launch as it takes a larger role in local policing.

In a meeting with the groups, Mr. Garland said he views sweeping investigations like the one launched Wednesday in Minneapolis as a powerful tool toward building trust between officers and their communities, people who attended the meeting told the Wall Street Journal.

He described the so-called pattern-or-practice investigations as a return to the sort of oversight the Trump administration sharply curtailed, one of the people said.

The meeting was the first of what Mr. Garland said will be many interactions between top Justice Department officials and police as the agency embarks on an ambitious civil-rights agenda that focuses in particular on federal involvement in overhauling troubled local agencies.

Police organizations supported Mr. Garland’s confirmation, telling senators they viewed him as someone with respect for law enforcement. But privately, some said they aren’t personally familiar with him, as they said his status as a sitting judge kept him from formally meeting with them during his confirmation process.

On the U.S. Court of Appeals for the District of Columbia Circuit, he was more inclined than other Democratic appointees to side with prosecutors and law enforcement in close criminal cases. And he was a federal prosecutor in the U.S. attorney’s office in Washington in the early 1990s, where he worked closely with city police officers.

"A number of FOP members remain close to Garland from those days," said Jim Pasco, executive director of the National Fraternal Order of Police. "We look forward to renewing that close working relationship which we have enjoyed with him in the past."