A MINNESOTA prosecutor has announced an investigation that may lead to charges against federal officers, including Border Patrol official Greg Bovino, for misconduct during an immigration enforcement crackdown.

Hennepin County Attorney Mary Moriarty told a news conference on Monday that her office was already looking into 17 cases, including one where Mr Bovino threw a smoke canister at protesters on January 21. 

Another on January 7 involved federal officers making an arrest outside a secondary school and deploying chemical irritants while students and staff were in the area.

“Make no mistake, we are not afraid of the legal fight and we are committed to doing this correctly,” Ms Moriarty said. “Operation Metro Surge caused immeasurable harm to our community.”

The Department of Homeland Security (DHS), which oversees immigration enforcement, responded in a statement that such enforcement is a federal responsibility and states cannot prosecute federal officers.

“What these states are trying to do is unlawful and they know it,” the statement said. “Federal officials acting in the course of their duties are immune from liability under state law.”

The statement added that local officials should instead consider how their actions had endangered federal law enforcement officers.

Mr Bovino, who did not immediately respond to a request for comment, is known for using aggressive tactics during operations in Minneapolis-St Paul, Chicago and Los Angeles. 

He was eventually removed from his leading role in the Minnesota effort after federal officers shot dead mother Renee Good and nurse Alex Pretti on different days in January, leading to nationwide demonstrations and widespread condemnation of DHS use-of-force policies.

Ms Moriarty’s office is also investigating the deaths of Ms Good and Mr Pretti and she is “confident” it will be able to press charges.