Washington (CNN) Former Trump national security adviser Michael Flynn, using new lawyers, has fully turned on the prosecutors who cut his guilty-plea deal and who recommended to a judge last year he avoid jail.

His attorneys say prosecutors, including Brandon Van Grack, who worked for special counsel Robert Mueller, have retaliated against him in recent weeks. Flynn had been preparing for months to help them at the trial of his ex-lobbying partner, Bijan Kian, until prosecutors dropped him as a witness at the beginning of the month.

Flynn's legal team says what he planned to say as a witness wasn't what the prosecutors wanted. But prosecutors claim Flynn was changing his story.

"Should the government's case here fail, it will not be because of anything Mr. Flynn did or did not do," his attorneys wrote on Thursday.

It's all part of a long turn for Flynn from being a key Mueller cooperator to a hostile defendant.

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