Maria Butina shown in 2013 in Moscow at a rally for gun rights. (AP)

Russian gun rights activist Maria Butina will be sentenced April 26 after pleading guilty in December to conspiring with a senior Russian official to infiltrate conservative American political circles by acting as an undeclared agent for the Kremlin, a federal judge ordered Thursday.

U.S. District Judge Tanya S. Chutkan set sentencing in Washington, D.C., after Assistant U.S. Attorney Erik Kenerson said prosecutors were ready, signaling Butina had completed her cooperation with investigators probing her efforts on behalf of the Russian government to forge ties with gun rights advocates at the National Rifle Association and other U.S. conservatives leading up to the 2016 U.S. election.

Butina, 30, admitted to working at the direction of Alexander Torshin, a Russian former government official, and with an American political operative to forge connections with NRA officials, conservative leaders and 2016 presidential candidates, including Donald Trump.

In her plea deal, Butina said she began to act on behalf of the Russian government in 2015 and continued her work after moving to the United States to attend graduate school at American University in 2016.

Since she pleaded guilty and started cooperating with the government, Butina was interviewed once by prosecutors with special counsel Robert S. Mueller III’s office, a debriefing that lasted about an hour, according to a person familiar with the interview.

Her case has otherwise been handled entirely by the U.S. attorney’s office in Washington, D.C., a sign prosecutors saw it as unrelated to President Trump and his 2016 election win.

Mueller formally concluded his investigation into Russian election interference and last week submitted his final report to Attorney General William P. Barr. Barr has said that Mueller did not establish a criminal conspiracy between anyone associated with Trump and Russia to affect the election and that he has recommended no additional indictments as part of his investigation.

Butina’s attorney, Robert N. Driscoll, has said the former graduate student was ready to learn her punishment, which previously had been delayed when prosecutors said they still might need her cooperation in contingent matters.

It was not clear what the status of Butina’s case might mean for the Republican operative with whom she worked. He has been identified by government officials as Paul Erickson, a longtime GOP political adviser from South Dakota who managed the 1992 presidential campaign of Pat Buchanan.

Erickson, who was also Butina’s boyfriend according to statements in court, was indicted in February in South Dakota over what federal prosecutors contend was an unrelated investment-fraud scheme.

Erickson’s attorney, William Hurd, has said his client is a “good American” who “has never done anything to hurt our country and never would.”

Butina has been in custody since being charged in July and that time served probably would be a substantial portion of whatever sentence she faces, the judge has said.

Butina is expected to be deported to Russia after completing her sentence, according to plea filings.