"She is on track," Driscoll said on Monday. "It should be the [October] 25th."
On 26 April, a US federal judge sentenced Butina to 18 months in prison after she pleaded guilty to the charge of conspiring to act as an unregistered foreign agent in the United States.
Butina, who signed the plea deal after being held for prolonged periods in solitary confinement, had requested a sentence of time served. She is imprisoned in the Federal Correctional Institution Tallahassee in the US state of Florida, according to the Federal Bureau of Prisons.
The Russian Foreign Ministry has called Butina's sentence a disgrace of the US judicial system and has accused the court of carrying out a political order.
Russian President Vladimir Putin said Butina’s indictment is unjustified because she was not tasked to perform any mission on behalf of the Russian government.