A day after a federal immigration officer fatally shot a woman in Minneapolis, the case escalated sharply Thursday when federal authorities blocked state investigators from accessing evidence and declared that Minnesota has no jurisdiction to investigate the killing.

Legal experts said the dispute highlights a central question raised repeatedly as federal agents are deployed into cities for immigration enforcement: whether a federal officer carrying out a federally authorized operation can be criminally investigated or charged under state law.

The FBI told Minnesota law enforcement officials they would not be allowed to participate in the investigation or review key evidence in the shooting, which killed 37-year-old Renee Good on Wednesday. Local prosecutors said they were evaluating their legal options as federal authorities asserted control over the case.

Minnesota Gov. Tim Walz urged federal officials to reconsider, saying early public statements by Homeland Security Secretary Kristi Noem and other federal leaders defending the agent risked undermining confidence in the investigation’s fairness.

Experts say there’s narrow precedent for state charges. And sometimes attempts at those charges have been cut short by claims of immunity under the Constitution’s Supremacy Clause, which protects federal workers performing federally sanctioned, job-related duties. But that immunity isn’t a blanket protection for all conduct, legal experts said.

What is the standard for immunity?

If charges are brought, the federal agent is likely to argue he is immune from state prosecution under the Supremacy Clause of the U.S. Constitution.

“The legal standard basically is that a federal officer is immune from state prosecution if their actions were authorized by federal law and necessary and proper to fulfilling their duties,” said Robert Yablon, a professor at the University of Wisconsin Law School.

Yablon, who is the faculty co-director of the school’s State Democracy Research Initiative, said state prosecutors would have to consider both state and federal laws to overcome the hurdles of immunity. They would first need to show a violation of state statutes to bring charges, but also that the use of force was unconstitutionally excessive under federal law.

“If the actions violated the Fourth Amendment, you can’t say those actions were exercised under federal law,” he said, referring to the constitutional protection against unreasonable searches and seizures by the government.

Hurdles to state charges

The whole endeavor is made more complicated if there is not cooperation between federal and state authorities to investigate the shooting.

Walz said federal authorities rescinded a cooperation agreement with the Minnesota Bureau of Criminal Apprehension, and he urged them to reverse course, warning that Minnesotans were losing confidence in the investigation’s independence. Noem confirmed the decision, saying: “They have not been cut out; they don’t have any jurisdiction in this investigation.”

State officials have been vocal about finding a way to continue their own parallel investigation.

Minnesota Attorney General Keith Ellison said during an interview on CNN that the move by federal authorities to not allow state participation does not mean state officials can’t conduct their own investigation.

But local officials in Hennepin County said they’d be in the dark if the FBI chose not to share their findings. Hennepin County Attorney Mary Moriarty said in a statement that her office is “exploring all options to ensure a state level investigation can continue.”

“If the FBI is the sole investigative agency, the state will not receive the investigative findings, and our community may never learn about its contents,” she said.

Deputy Attorney General Todd Blanche defended federal agents’ use of force, saying Thursday that officers often must make split-second decisions in dangerous and chaotic situations. In a statement posted on social media, Blanche said the law does not require officers “to gamble with their lives in the face of a serious threat of harm,” and added that standard protocols ensure evidence is collected and preserved following officer-involved shootings.

In many cases involving use-of-force, investigators examine how the specific officer was trained, if they followed their training or if they acted against standard protocol in the situation. It’s unclear if state investigators will be granted access to training records and standards or even interviews with other federal agents at the scene Wednesday, if they continue a separate investigation.

During the prosecution of former Minneapolis police officer Derek Chauvin in the killing of George Floyd, prosecutors called one of the department’s training officers to testify that Chauvin acted against department training.

Precedents and other legal issues

Samantha Trepel, the Rule of Law program director at States United Democracy Center and a former prosecutor with the Justice Department’s civil rights division, wrote a guest article for Just Security Wednesday in the wake of the fatal shooting. The piece focused on the Department of Justice silence in the face of violent tactics being used in immigration enforcement efforts.

Trepel, who participated in the prosecution of officers involved in Floyd’s death, told AP Thursday that the current DOJ lacks the independence of previous administrations.

“In previous administrations, DOJ conducted independent and thorough investigations of alleged federal officers’ excessive force. Even though the feds were investigating feds, they had a track record of doing this work credibly,” Trepel said. “This included bringing in expert investigators and civil rights prosecutors from Washington who didn’t have close relationships and community ties with the individuals they were investigating.”

Trepel said in a standard federal investigation of alleged unlawful lethal force, the FBI and DOJ would conduct a thorough investigation interviewing witnesses, collecting video, reviewing policies and training, before determining whether an agent committed a prosecutable federal crime.

“I hope it’s happening now, but we have little visibility,” she said. “The administration can conduct immigration enforcement humanely and without these brutal tactics and chaos. They can arrest people who have broken the law and keep the public safe without sacrificing who we are as Americans.”

Questions about medical aid after the shooting

In other high-profile fatal police shootings, officers have faced administrative discipline for failing to provide or promptly secure medical aid after using force.

Video circulating from Wednesday’s shooting shows a man approaching officers and identifying himself as a physician, asking whether he could check Good’s pulse and provide aid. An agent tells him to step back, says emergency medics are on the way, and warns him that he could be arrested if he does not comply.

Witness video later showed medics unable to reach the scene in their vehicle, and people carrying Good away. Authorities have not said whether actions taken after the shooting, including efforts to provide medical assistance, will be reviewed as part of the federal investigation.

In other cases, including the 2023 death of Tyre Nichols in Memphis, Tennessee, failures to render medical aid were cited among the reasons officers were fired and later charged.

Crowds gathered in Minneapolis on Wednesday to protest and hold a vigil for a woman killed during the Trump administration’s latest immigration crackdown.

The Minneapolis motorist was shot during an Immigration and Customs Enforcement operation in the city in what federal officials claimed was an act of self-defence by an officer, but which the city’s mayor described as ‘reckless’ and unnecessary