CHICAGO — Gregory Bovino, a senior Border Patrol official, appeared to lob a tear-gas canister into an irate crowd of Chicago residents on Thursday, videos showed, during a chaotic confrontation between the public and Border Patrol agents in the Little Village neighborhood.

Plaintiffs in a lawsuit against the Department of Homeland Security over tactics federal agents have used during an illegal immigration crackdown in the Chicago area said that Bovino had violated a court order by “apparently throwing tear gas into a crowd without justification.”

This month, a coalition of media organizations, protesters and clergy members filed the lawsuit, which accused agents of “a pattern of extreme brutality” intended to “silence the press and civilians.”

Judge Sara L. Ellis of U.S. District Cour

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