Former federal prosecutor and Fox News contributor Andrew McCarthy joined Brian Kilmeade on "Fox & Friends" Thursday morning to explain why he believes Special Counsel Robert Mueller's investigation is coming to a close.

Mueller this week filed a sentencing memo for Michael Flynn, President Trump's former national security adviser.

In the highly redacted memo, Mueller recommended little to no prison time for Flynn, stating that the former three-star Army general has offered "substantial" help to investigators about "several ongoing investigations." Flynn, who pleaded guilty to lying about his conversations with a Russian official, is set to be sentenced Dec. 18.

The bombshell release came as additional sentencing memorandums are expected within days in the cases of former Trump attorney Michael Cohen and ex-campaign chairman Paul Manafort.

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McCarthy said these developments are an indication that the Mueller probe is "winding down."

He explained that prosecutors do not let cooperating witnesses get sentenced until they are near the end of the investigation, because prosecutors must be able to make a full appraisal of how cooperative a witness has been.

He added that the sentencing memo also indicates that Mueller is trying to justify the FBI's investigation.

"That is to say, even if they don't find that there was citable, criminal conduct on the part of President Trump, they will say that there was adequate reason for the FBI and the Obama administration very controversially to launch an investigation of the opposing party's campaign," McCarthy said.

Watch the "Fox & Friends" interview above.

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