US prosecutors have notified Erickson's lawyer that they are considering bringing charges against him under the law, which prohibits US citizens from secretly acting as foreign government agents, The Daily Beast reported, citing a "target letter" sent to the attorney by federal prosecutors.
Erickson also may face a criminal conspiracy charge, the document reportedly said.
READ MORE: Russian National Butina Withdraws Motion to Dismiss US Indictment
The letter was sent in September and does not guarantee that Erickson will face any charges, the report said. However, it noted, if prosecutors move forward with their apparent intentions, Erickson could become the first American publicly accused of acting as a foreign agent in the so-called "Russia's investigation."
Last week, Butina’s defence team called on US authorities to transfer the defendant to the general prison population after she was forced to spend more than nine weeks in administrative segregation housing, also known as solitary confinement, however, US Judge Tanya S. Chutkan didn't allow the transfer.
Butina, a recent American University student and political activist, was arrested in Washington, DC in mid-July on suspicion of acting as an agent for a foreign government. She has denied the accusations. Butina, who faces up to 15 years in jail, is now being held in a prison in the US city of Alexandria, Virginia.
READ MORE: US Judge ‘Dismayed' by Farcical Retracted Sex Allegations Against Mariia Butina
Russian authorities have slammed the US government for Butina's arrest, insisting that the charges against her are groundless. The Russian Foreign Ministry has called Butina's ongoing detention unacceptable and has called the accusations trumped-up.