(CNN) Paul Erickson, the former boyfriend of Maria Butina, agreed to plead guilty this week to two charges in South Dakota federal court -- money laundering and wire fraud -- with one of the criminal transactions sent to a person with the initials "M.B."

He admits, in the money laundering count, to transferring $1,000 to M.B., and that money "represented the proceeds of some form of unlawful activity," according to his indictment.

That unlawful activity was a fraudulent payment he received, according to his plea deal paperwork, where he took a $100,000 business investment payment and failed to invest it in North Dakota oil field real estate development as he had promised.

Prosecutors dropped nine other money laundering charges Erickson had faced. All of those related to people with initials other than "M.B.," although Erickson had allegedly transferred about $20,000 in June 2017 to American University, where Butina attended grad school, according to his original indictment

Erickson was indicted in February. After Butina's arrest in Washington, DC, she cooperated with investigators, including by giving information about Erickson, who was under investigation in DC, but was not charged.

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