They asked nicely at first.

After an Immigration and Customs Enforcement agent shot and killed Renee Good, a 37-year-old mother of three who’d recently moved to Minneapolis, local law enforcement officials requested a partnership with the federal government to investigate the case, as they’d done in past shootings involving federal agents.

When the Trump administration refused to cooperate, Minnesota prosecutors ratcheted up their efforts. They sent a series of strongly worded legal letters demanding evidence in the Good shooting as well as the shootings of Julio Cesar Sosa-Celis, a Venezuelan immigrant who was wounded a week after Good was shot, and Alex Pretti, who was killed on Jan. 24.

Still, the administration rebuffed the requests.

This week, prosecutors from Hennepin County and the state of Minnesota took the next step to force the Trump administration’s hand. They filed a federal lawsuit against the departments of Homeland Security and Justice over the evidence in the shootings, an action that Hennepin County Attorney Mary Moriarty, whose jurisdiction covers Minneapolis, characterized as “unprecedented in American history.”

The Trump administration has declined to release the names of the agents involved in the shootings, even after the Minnesota Star Tribune and ProPublica identified the officers involved in the Good and Pretti incidents.

“The federal government has refused to cooperate with state law enforcement, which is unique, rare and simply cannot be tolerated,” Minnesota Attorney General Keith Ellison told reporters. “[We] can’t sit around and let them do it.”

In the standoff over evidence, the case has already become a game of constitutional chicken over states’ rights versus federal immunity, a battle that will have implications for others who wish to hold agents in the president’s immigration surge criminally accountable.

So far, neither side is showing signs of backing down, foreshadowing a fight that could take years. If prosecutors do eventually file charges against federal agents involved in the shootings, legal experts said the path to trial, much less winning convictions, will be filled with legal and procedural challenges.

“State prosecutors across the country are going to be watching what happens in Minnesota really closely,” said........

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