Rick Gates, center, arrives at a federal courthouse in Washington in January 2018. (Chip Somodevilla/Getty Images)

Special counsel Robert S. Mueller III on Tuesday asked a federal judge to again delay sentencing for Rick Gates, saying the top deputy to former Trump campaign chairman Paul Manafort continues to cooperate with investigators.

The request was joined by his defense team.

“Defendant Gates continues to cooperate with respect to several ongoing investigations, and accordingly the parties do not believe it is appropriate to commence the sentencing process,” both sides wrote in a one-page update for U.S. District Judge Amy Berman Jackson of the District.

The reference to Gates’s cooperation echoed language used in November, suggesting his assistance extended beyond the testimony he gave in Manafort’s August trial in Virginia. As both sides did in November, Tuesday’s filing proposed updating the court about whether to set a sentencing date for Gates in another 60 days, on March 15.

Gates worked closely for years as Manafort’s right-hand man, as a political consultant in Ukraine and as his deputy on the presidential campaign. But after Manafort resigned from the Trump campaign in August 2016, Gates remained in Trump’s orbit, working as a campaign adviser until the election. He then helped organize Trump’s inauguration.

Prosecutors typically delay sentencing for witnesses until their help is no longer needed, including in testifying before a grand jury or at trial.

Gates pleaded guilty in February to reduced charges of lying to the FBI and conspiring against the United States and agreed to cooperate with Mueller. He faces about five to six years in prison under sentencing guidelines, but his cooperation could prompt the government to ask for significantly less time.