with reporting by Paula Reid

WASHINGTON — Maria Butina, who has been accused of spying for Russia, will plead guilty to a single count of conspiracy, according to a source familiar with her case. As part of the plea agreement, she will also cooperate with the Justice Department's investigation, which is not related to special counsel Robert Mueller's Russia probe. Her lawyers are asking for a sentence of 0 to 6 months, and this is a felony conviction, so she will face deportation.

Butina has been in solitary confinement in a Virginia jail. On Monday morning, Butina's attorneys and federal prosecutors filed a joint motion to schedule a "change of plea" hearing before the D.C. District Court. "The parties have resolved this matter," the court document read.

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Butina, a 30-year-old Russian national, was indicted and arrested in July on charges of conspiracy and acting as a foreign agent. The case was investigated by the FBI's Washington, D.C. field office, with charges brought by the U.S. attorney's office of the District of Columbia and the National Security Division of the Justice Department.

Prosecutors alleged that Butina violated U.S. espionage laws by infiltrating U.S. political groups on behalf of a high-ranking official in Russian President Vladimir Putin's inner circle, Alexander Torshin, a deputy governor of the Russian Central Bank. Butina pleaded not guilty to the charges.

Last month, a federal court rejected a request by Butina's attorneys to remove her from solitary confinement. Her lawyers cited a lack of "meaningful human contact" and "sensory stimulation" in prison.

Clare Hymes and Rob Legare contributed to this report.