Dr. John Manchin II filed the lawsuit in Marion County against the senator and Roch Manchin.
The lawsuit, filed Wednesday, says Joe and Roch Manchin received a loan of more than $1.7 million from John Manchin in the late 1980s to help the then-struggling business with the promise of repayment. No payments have been made.
John Manchin says that a July 2012 agreement made by the brothers allowed him to take one-third interest in coal and other related businesses by Joe and Roch Manchin if there was a delay in repayment.
But the lawsuit says the brothers' general partnership was dissolved without John Manchin's knowledge, with funds and assets transferred to a partnership controlled by Joe Manchin and his son, Joseph Manchin IV.
The lawsuit seeks unspecified compensation for John Manchin's losses and the awarding of one-third ownership in all coal reserves and businesses formed through the brothers' partnership.
Jonathan Kott, a spokesman for the senator, said the lawsuit was a family matter and declined comment Friday. Roch Manchin didn't immediately return a telephone message left at his carpet business.
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