Whistle-Blower’s Complaint Ignites a Smoldering Homeland Security Agency

“Why did D.H.S. come into existence? It came in to share information that state and local partners weren’t getting,” said Chuck Wexler, the executive director of the Police Executive Research Forum, a law enforcement policy organization. “It filled a void that didn’t exist. So if you start to filter that information, we’re back to square one.”

Mr. Murphy is currently preparing for interviews about the intelligence office with the inspector general of the Homeland Security Department and the House Intelligence Committee. The committee has been investigating the department’s intelligence branch since July after the office authorized analysts to collect information on protesters who damaged statues and monuments. The committee has received internal documents and is preparing to interview witnesses on the agency’s deployment of tactical agents to Portland, Ore.

Representative Adam B. Schiff, the chairman of the committee, said in a letter on Friday that it had expanded its investigation to include the “improper politicization of intelligence and political interference.” The Republican-led intelligence committee in the Senate notified the department on Thursday that it, too, would investigate on a bipartisan basis claims made by Mr. Murphy.

Mr. Murphy is expected to testify on Sept. 21 in a closed-door session with the committee. The House Homeland Security Committee also issued a subpoena to Mr. Wolf to testify in a public hearing on Sept. 17 after he refused to commit to doing so by citing his pending nomination.

He has gone from accused to accuser in a matter of weeks. Previous witnesses against the Trump administration, such as Alexander S. Vindman and Marie L. Yovanovitch, have been painted by critics of the president in golden hues. Mr. Murphy is more complicated: Last month, Mr. Schiff said he was concerned Mr. Murphy had misled Congress over the office’s intelligence gathering methods during the unrest in Portland.

Mr. Murphy, a conservative Republican who supported Mr. Trump in 2016, saw the senior intelligence position at homeland security as a logical next step for his counterterrorism career, former officials who worked with him said. His work at the F.B.I. earned him the nickname T-1000, after the almost indestructible, relentless android in the movie “Terminator 2.”

But his brusque style and penchant for going alone over repeated warnings from superiors to hew more closely to the rules ultimately stalled his career at the F.B.I. before he could land a plum assignment running a field office, a former senior law enforcement official said.