Washington (CNN) Federal prosecutors say former Donald Trump campaign aide Rick Gates should receive probation for his work with special counsel Robert Mueller's investigation, a major boost for one of the most damaging witnesses against the Trump campaign for Mueller.

In a court filing Tuesday , prosecutors describe how Gates testified against Paul Manafort, Roger Stone and Greg Craig, and recounted details about Trump on the campaign trial. They note he has helped them with at least one ongoing investigation-- and still could help with unnamed matters.

"Gates has provided significant information contributing to the convictions of Manafort and Stone, and to other investigation(s) that are ongoing," prosecutors wrote in a memo to federal Judge Amy Berman Jackson in Washington, DC.

In all, Gates met more than 50 times with prosecutors and investigators at the Justice Department and they've used what he's helped them with on more than 12 search warrants, the prosecutors said. Gates' own legal team estimated the amount of time he spent giving prosecutors information at more than 500 hours. His own lawyers asked the judge to sentence him to probation and community service, with no fines.

Prosecutors added that Gates would agree to cooperate with prosecutors again in the future, and that the judge could make this part of his sentence. Additional information about Gates' ongoing cooperation efforts appears to be filed under seal with the federal court.

Read More