A highly anticipated filing from special counsel Robert Mueller was revealed Tuesday evening in his investigation into Russian election interference and alleged collusion with the Trump campaign.

'Substantial assistance'

The filing was in relation to recommendations for the sentencing of Gen. Michael Flynn, the former national security adviser to President Donald Trump.

The filing says that Mueller recommends no prison time for Flynn after he has provided the investigation with "substantial assistance" in the investigation.

"Given the defendant's substantial assistance and other considerations set forth below," the filing read, "a sentence at the low end of the guideline range — including a sentence that does not impose a term of incarceration — is appropriate and warranted."

Mueller indicated that Flynn had already participated in 19 interviews in the criminal investigation.

However, much of the filing is redacted in the publicly released documents.

Catherine Herridge of Fox News indicated that Flynn could have faced up to five years of prison time for the charges he plead guilty to, which included lying to federal investigators.

'General Flynn lies to the FBI and his life is destroyed'

Trump has tweeted in the past in support of Flynn, saying that Mueller had "totally destroyed" his life unfairly.

In another tweet from December 2017, the president defended his actions in firing Flynn as his national security adviser, and pointed to the lies he admitted telling Vice President Mike Pence and the FBI.

Flynn's son responded to the filing and recommendation for no prison time from his social media account.

"God is good," he tweeted. "To those who have supported us throughout this process.... Thank you from the bottom of my heart."

"I will never forget you," he added.

Here's the Fox News report on the development: