The U.S. Attorney's Office says Jafaar Nyangoro and his accomplice from Germany gained access to the email account of a Fresno nonprofit.
Prosecutors say the pair instructed the county that money for the nonprofit should be sent to a different account.
But communications between the men show the bank reversed some transfers for suspected fraud.
Nyangoro and his accomplice then realized that the authorities had discovered their scheme.
Nyangoro is scheduled to be sentenced in September and faces the maximum sentence of 20 years in federal prison.
In a statement, a Fresno County spokesperson said: "The County of Fresno is grateful to the FBI for conducting a thorough investigation that empowered the U.S. Attorney's Office in the Eastern District of California to pursue this case. Mr. Nyangoro defrauded the taxpayers of Fresno County, and we trust the U.S. District Court will impose the maximum sentence commensurate with the seriousness of his actions."