ANKARA

A Democratic senator is warning that the US Department of Homeland Security’s internal watchdog may be losing its independence after repeated reminders from the department’s legal team that Homeland Security Secretary Kristi Noem has the authority to shut down investigations.

In a letter to Noem obtained by NBC News, Sen. Tammy Duckworth said DHS Inspector General Joseph Cuffari was repeatedly told by the department’s general counsel that the secretary “has the power to kill investigations” conducted by the Office of Inspector General.

Duckworth also said the OIG was asked on Jan. 29 to disclose “every active audit, inspection and criminal investigation,” a request she described as “extremely unusual, perhaps even unprecedented.”

She warned that what she called “repeated tacit threats” may have weakened the inspector general’s operational independence, particularly in the days following the fatal shooting of US citizen Alex Pretti by Border Patrol agents.

Former Interior Department inspector general Mark Greenblatt said federal law under the Inspector General Act of 1978 does allow Cabinet secretaries to block investigations if they determine national security would be harmed. However, he said that authority has never been used in practice.

“In my experience that provision has never been invoked by any agency across the federal government,” Greenblatt said.

He added that notifying a Cabinet secretary about criminal investigations is highly unusual, noting that law enforcement agencies typically do not disclose such information in advance. “The FBI doesn’t tell everyone what they are investigating in advance,” he said.

DHS Assistant Secretary Tricia McLaughlin defended the authority, saying it “has been in place for decades,” and added that lawmakers have the power to change the law if they choose.

Separately, the DHS Office of Inspector General said Thursday that it is reviewing the department’s immigration enforcement practices, including Immigration and Customs Enforcement hiring, detention conditions, and the use of agents in cities such as Los Angeles, Chicago, and Minneapolis.