Homeland Security Secretary Kirstjen Nielsen Is Out

Homeland Security Secretary Kirstjen Nielsen abruptly resigned Sunday evening.

Her departure comes after lengthy and consistent calls for her resignation over family separation policies at the border and the death of at least one transgender refugee in the care of Immigration and Customs Enforcement.

President Donald Trump tweeted out the news and named Customs and Border Protection Commissioner Kevin McAleenan as his pick for a replacement.

Nielsen, while initially saying Sunday would be her last day, agreed to stay on the job only through Wednesday.

Despite a rapid departure that suggests some urgency to her separation from the administration, Nielsen in a letter posted on Twitter said she was "immensely proud" of agency successes.

"Despite our progress in reforming homeland security for a new age, I have determined that it is the right time for me to step aside," she wrote.

Many hoped she would move along much sooner. Hundreds of fellow Georgetown University alumni called on her to resign last June.

She's also leaving just as ICE dramatically expands the number of beds it keeps in child detention centers despite the many administrative problems experienced by ICE regarding its family separation policy. That has included a surge in the number of babies detained by ICE at the border.

There still remains no answers about the death of 33-year-old Roxsana Hernandez, a Honduran asylum seeker who died in a new Mexico detention center.

While the official cause of death listed was complications with pneumonia and HIV, an independent autopsy by the Transgender Law Center said the trans woman suffered physical abuse in custody as officials ignored her vomiting and severe diarrhea. Three U.S. senators sent a letter to ICE demanding an explanation.

As of February, at least 111 trans individuals were in ICE custody, officials said.

Nielsen was the sixth secretary of Homeland Security, an agency formed to protect the country from terrorists after 9/11. Through Nielsen's tenure, the stories constantly in the news involved the detention of political refugees.