A participant in the protracted lawsuit over production rights to the work of the late artist Robert Indiana asked a federal court to order the estate to abide by a supposed binding mediation agreement that would settle the case.

Michael McKenzie, of American Image Art, filed the complaint July 26 in U.S. District Court in Portland.

Indiana died at his home on Vinalhaven in May 2018 at the age of 89. His estate is valued at nearly $100 million. His will bequeathed his estate to the Star of Hope Foundation, which would turn his longtime home on the island into a museum.

After his death, litigation arose between Indiana's estate American Image and other parties.

The dispute led to high stakes federal lawsuits in New York.

According to the new complaint from McKenzie, Attorney General Aaron Frey, who has supervisory authority over statewide charities, directed the estate and American Image to submit their dispute to binding mediation in Maine.

As of Jan. 6, litigation costs exceeded $3,750,000, according to the McKenzie lawsuit.

A binding mediation was reached after a mediation session was held in Portland in November 2019, according to the lawsuit.

Terms of that mediation agreement have not been released but, according to the lawsuit, among other provisions obligated the parties to discontinue the New York arbitration since all their disputes were resolved by the agreement negotiated in Maine.

However, the Indiana estate now refuses to honor its commitments, the McKenzie lawsuit claims, which could cost the estate millions of dollars.

Attorney James Brannan of Rockland responded July 28 to the new claim. Brannan represents the estate.

"This is Mr. McKenzie’s fourth law firm. He and his last attorney agreed to a written confidential settlement in November. Within days, he refused to honor it and sent a letter to many media outlets. Now, eight months later, the newest law firm wants to resurrect it. The estate is moving forward, not backward," Brannan said.

A federal lawsuit filed by the Morgan Art Foundation in New York in May 2018 — the day before Indiana died — accused Indiana's longtime caretaker Jamie Thomas and McKenzie of isolating and exploiting Indiana, forging his art and exhibiting some of the forgery in museums.

Thomas and the estate were also battling in state court. Thomas wanted the estate to cover his legal expenses while the estate claimed that Thomas, who served as a caretaker for Indiana, took advantage of the elderly artist before his death.

That lawsuit was settled following a November mediation, Terms have not been released.