The heavy hand of Stephen Miller, White House senior adviser for policy, is now clearly evident in his continuing "purge" of the Department of Homeland Security (DHS), which saw three of its top executives fired on three successive days.

The newest casualty of Miller's campaign to install new DHS leadership is DHS Acting Deputy Secretary Claire Grady, who was fired Tuesday.

As with the case of her boss, former DHS Secretary Kirtsjen Nielsen fired on Sunday, and former Director of the U.S. Secret Service Adolph Alles fired on Monday, Grady was seemingly forced to resign. The White House, however, claimed Grady was leaving voluntarily of her own behest and wasn’t fired.

As with Nielsen and Alles, Grady received White House praise for her service to the nation. In Grady's case, she was exalted for her "excellence and distinction. She has been an invaluable asset to DHS -- a steady force and a knowledgeable voice.”

Two more DHS officials are expected to be fired,: U.S. Citizenship and Immigration Services director Francis Cissna and John Mitnick at the Office of the General Counsel.

Grady, however, was resigned to her fate after Nielsen’s sacking. A former DHS official told CNN she "knew her fate was tied to Nielsen," and that she would be next on the chopping block.

"She is one of the people who got stuff done at DHS. Someone everyone went to at the department when they were having a bad day," said this former official. Media reports confirm Miller played the key role in Nielsen’s sudden ouster.

Another official described the DHS movement as "a near-systematic purge happening at the nation's second-largest national security agency."

In his “near systematic purge” of the DHS, Trump has given Miller carte blanche to lead the administration's border policies "and he's executing his plan" with what amounts to a wholesale decapitation of the DHS leadership, said an administration official quoted by media.

Grady's firing and the continuing leadership purge points to Trump packing the new DHS leadership with people that will redirect the agency towards immigration enforcement.

GettyImages-825652924 Senior Advisor to the President for Policy Stephen Miller talks to reporters. Miller is playing the key role in purging the senior leadership of the Department of Homeland Security. Photo: Chip Somodevilla/Getty Images

Nielsen was known to have run afoul of Trump when she told him it would be against the law for Trump to resume the forced separation of migrant families at the southern border. A federal court had declared this policy illegal.

Transportation Security Administration Administrator David Pekoske is expected to be named acting deputy secretary replacing Grady.