Former CNN anchor Don Lemon has hired a federal prosecutor, who quit amid the White House’s immigration blitz on Minneapolis, to defend him from charges related to his coverage of a church protest.

Lemon officially brought Joseph H Thompson on to his legal team, according to a Tuesday court filing. Thompson, who Donald Trump had appointed acting US attorney for Minnesota in June, reportedly resigned in January over the justice department’s treatment of immigration enforcement.

A federal grand jury in Minnesota indicted Lemon, now an independent journalist, on charges of conspiracy and interfering with congregants’ constitutional rights to freely exercise their religion during an 18 January protest at the Cities church in St Paul. Others were arrested in connection with this protest.

A US Immigration and Customs Enforcement (ICE) official serves as a pastor at the church. The demonstration unfolded 11 days after an immigration officer shot and killed Renee Nicole Good as she was driving away from an encounter with agents.

Border patrol agents fatally shot Alex Pretti, who like Good was a US citizen, after disarming and restraining him, six days later. The veterans hospital nurse was licensed to carry a firearm and did not break the law in doing so.

Thompson reportedly left the Minnesota US attorney’s office over disagreements with higher-ups about investigating Good’s death at the hands of an immigration agent. Thompson and other longtime prosecutors wanted to investigate Good’s death, but justice department officials disagreed, wanting to investigate Good’s partner instead over alleged ties to anti-ICE groups, the New York Times reported.

Thompson launched his own law firm with Harry Jacobs, another federal prosecutor who quit over the justice department’s handling of Minneapolis, per the Times. He served as acting US attorney until October and then returned to the top post of first assistant US attorney in Minnesota, according to his LinkedIn.

CNN noted that Thompson’s high-profile cases include sprawling fraud scandals that have dogged Minnesota for years, the political fallout of which shaped Governor Tim Walz’s decision to abandon his re-election bid. This includes prosecutors’ Feeding Our Future case, which resulted in convictions for a $250m pandemic aid fraud scheme.

Lemon insisted that he is not affiliated with the protesters who interrupted the proceedings by going into the church. He said he was not among the demonstrators.

“I went there to be a journalist,” Lemon previously said. “I went there to chronicle and document and record what was happening. I was following that one group around, and so that’s what I did. I reported on them.”

Lemon has repeatedly noted that he was simply exercising his first amendment right – which enshrines freedom of the press and speech the US constitution. “Our society cannot breathe without the freedom of the press, the freedom of speech,” Lemon remarked at a recent human rights address in New York City.

“When the first amendment becomes optional, democracy becomes hollow,” Lemon said. “We [have] got to keep fighting. A free press is … one of the few places where power can still be questioned, where stories can still be told, where the voiceless can still be heard.”