PORTLAND — The owner of Scarborough Downs racetrack has filed a $12 million defamation suit against the estate of a former business partner who made unflattering comments that were quoted in a book.

Joseph Ricci said in a statement that he plans to sue the late Gerald E. Davidson as well as others who allegedly defamed him in the book, “Duck in a Raincoat.”

The suit filed in Cumberland County Superior Court contends that Davidson encouraged the writing of the book to coerce Ricci into buying out Davidson’s interest in businesses the two owned.

Ricci claims the book by his former employee Maura Curley depicts him “as a psychopath.” According to a review, the author interviewed more than 300 people in researching the book.

Ricci and Davidson, a Massachusetts psychiatrist who died in April of bone marrow disease, owned Scarborough Downs, several treatment centers for troubled adolescents and Golden Ark Enterprises Inc., a holding company.

The suit charges Davidson with trying for years to “systematically impugn” Ricci’s reputation, thus forcing Ricci into buying Davidson out.

Ricci, the suit says, bought Davidson’s shares in the businesses in March 1990 for $2 million in an effort “to bring to an end this long train of abuses of his rights and the rights of the corporations.”

During negotiations for the buyout, a promotional flier for the book was published saying that Davidson would call Ricci “a psychopath” in the book, Ricci maintains.

Ricci claims Davidson lied by denying the statement and signing an affidavit to that effect.

The lawsuit claims Davidson’s “clinical analysis of Ricci’s character” was the centerpiece of the book. Defendants in the suit are Rosalie Davidson and Robert Vigoda, executors of Davidson’s estate.