The Secret Service monitored Brenda Allen and her family for months. The surveillance came after an altercation with her neighbor, who worked for former Secret Service Director Mark Sullivan.​ (Theresa Poulson/The Washington Post)

The Secret Service director has called for a full investigation into allegations that agents were improperly ordered to abandon their posts monitoring the White House complex in 2011 and sent to provide protection for a friend of the agency’s former director.

Director Julia Pierson said late Sunday that she had contacted the Department of Homeland Security’s new inspector general to request a thorough review and wanted to ensure public trust in the elite law enforcement agency. Her actions came hours after The Washington Post reported that agents in a special surveillance unit were pulled off duty for at least two months in 2011 to go an hour’s drive away to the La Plata, Md., home of the then-director’s administrative assistant.

Agents were told that Director Mark Sullivan was concerned that his assistant, a close friend, was being harassed by a neighbor in her rural community. Inside the Secret Service’s Washington field office, the reassignment was known as Operation Moonlight, and agents were concerned that it increased the security risk to the president and the White House compound.

Pierson’s public comments came after the chairman of the House Intelligence Committee said on a CBS news broadcast that the Secret Service director would have “some explaining to do” about the diversion of agents and noted that Pierson had been Sullivan’s chief of staff during the 2011 episode. Mike Rogers (R-Mich.), chairman of the committee, also said that the agency appeared to have suffered another “leadership failure.”

Pierson said in her Sunday night statements that she looked forward to remedying any problems that DHS Inspector General John Roth uncovered in his probe.

“Director Pierson will ensure the Secret Service responds to any findings from this investigation and implements any recommendations or corrective actions identified by the DHS OIG as appropriate,” said Ed Donovan, a spokesman for the agency. “She is committed to ensuring public trust and confidence in the Secret Service through the professionalism and integrity of its workforce at all levels. Any allegations of impropriety or misconduct will be aggressively investigated and addressed.”

According to three people familiar with the assignment, Operation Moonlight pulled agents from a special unit called Prowler, assigned with patrolling the perimeter of the White House and monitoring public crowds on the South Lawn when the first family were traveling on and off the compound by helicopter and motorcade.

On the first day of the new operation, the two Prowler agents on duty were directed to leave their position on the Ellipse, the public park directly south of the executive mansion, minutes before President Obama departed on his helicopter. The aircraft’s movements on and off the South Lawn are highly visible to the public and are a matter of heightened security concern.

The agents thought the reassignment was a potentially illegal use of government resources. Concerned about their own liability, they kept records of their involvement and their superiors’ instructions.

Sullivan said in a statement to The Washington Post that he did not order the diversion of agents to the La Plata home of Lisa Chopey. He said he learned of it after the fact and thought that the checks lasted only a weekend and were appropriate to protect an agency employee who had complained that a neighbor was harassing her.

But Brenda Allen and Michael Mulligan, the couple who had a dispute with the Chopey family, said they felt stalked that summer. They said they noticed unmarked cars and SUVs parking behind their home and driving up and down their driveway for several months from June 30, 2011, through August. The couple said they were shocked to learn that their mysterious stalkers were Secret Service agents.

“I’m pretty upset to learn that’s how my tax dollars were used,” Allen said. “I think we all should be.”