Minneapolis live updates: DOJ launches investigation into Pretti killing, Deputy AG Blanche says

The American Federation of Government Employees, the largest federal employee union which also represented Alex Pretti, issued a statement Monday night calling for the resignations of DHS Secretary Kristi Noem and Deputy White House Chief of Staff Stephen Miller.

AFGE President Everett Kelley contended that their immigration policy and actions led to the nurse's death.

"Taken together, the actions of Miller and Noem, both before and after Alex's killing, make clear they are unfit to serve in their current positions, or any position requiring the public trust," Kelley added.

An online fundraising campaign set up in memory of Alex Pretti, who was killed in a shooting involving federal agents in Minneapolis on Saturday, has raised over $1.5 million.

-ABC News' Chris Looft

The chief federal judge in Minnesota says the Trump administration has failed to comply with orders to hold hearings for detained immigrants and ordered the head of Immigration and Customs Enforcement to appear before him Friday to explain why he shouldn't be held in contempt.

In an order dated Monday, Chief Judge Patrick J. Schiltz said Todd Lyons, the acting director of ICE, must appear personally in court. Schlitz took the administration to task over its handling of bond hearings for immigrants it has detained.

"This Court has been extremely patient with respondents, even though respondents decided to send thousands of agents to Minnesota to detain aliens without making any provision for dealing with the hundreds of habeas petitions and other lawsuits that were sure to result," the judge wrote.

The order comes a day after President Donald Trump ordered border czar Tom Homan to take over his administration's immigration crackdown in Minnesota following the second death this month of person at the hands of an immigration law enforcement officer.

The younger sister of Alex Pretti issued a statement Monday memorializing her big brother's kindness and criticizing "disgusting lies" told in the wake of his death.

Micayla Pretti called her brother a hero and thanked everyone who had reached out to the family with messages or posts she described as sharing the overwhelming positivity that reflected his character, work ethic and passions.

"All Alex ever wanted was to help someone - anyone," she said. "Even in his very last moments on this earth, he was simply trying to do just that."

Alex Pretti was an intensive care nurse, and through his work at the Veterans Administration, "he touched more lives than he probably ever realized," his sister said.

She lamented how some have portrayed her brother.

"When does this end? How many more innocent lives must be lost before we say enough?" Micayla Pretti asked. "Hearing disgusting lies spread about my brother is absolutely gut-wrenching."