(CNBC) — Former national security advisor Michael Flynn has given special counsel Robert Mueller “first-hand” details of contacts between President Donald Trump’s transition team and Russian government officials, Mueller said in a bombshell court document filed Tuesday night.

Mueller, in that sentencing memo, said Flynn’s “substantial assistance” to the special counsel’s probe over the past year warrants a criminal sentence for him on the low end of federal guidlines, which could include no jail time for the retired Army lieutentant general.

Mueller’s memo almost competely blacks out the details of what Flynn told the special counsel’s office.

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