Robert Indiana’s estate is selling two works from the late artist’s collection to fund its ongoing litigation. The works, by Ed Ruscha and Ellsworth Kelly, could fetch a combined sum of more than $4 million when they hit the auction block at Christie’s post-war and contemporary day sale on November 16.

The executor of Indiana’s estate, James W. Brannan, a lawyer in Maine, said the estate urgently needs money to cover mounting legal fees so it can continue to defend itself against a lawsuit filed in a Manhattan court. “Litigation is expensive, especially in New York,” Brannan said. The Ruscha work, Ruby, is estimated at $2 million-3 million, while Kelly’s Orange Blue is expected to fetch $900,000-1.2 million.

In the federal suit, filed shortly before Indiana’s death in May, the artist’s business manager accused Indiana’s caretaker and publisher of deliberately isolating the elderly artist. He also accused him of manufacturing and selling fake works attributed to Indiana, including a sculpture commissioned by a sausage manufacturer that said “BRAT” (for bratwurst), which was stylized in the same formation as the artist’s iconic “LOVE” series.

Critics of the upcoming auction argue that the estate should keep all of the works in its possession because they reveal invaluable insights into the artist’s personal relationships and artistic influences. John Wilmerding, emeritus professor of American art at Princeton University, points out that Indiana and Kelly were once in a relationship, and that Ruscha was also a pioneering word artist. “It’s tragic because those are major works,” he told the New York Times. “Somehow the estate ought to be kept together. Not just his own works, but the works that he collected or was given.”

The estate also needs money to repair Indiana’s crumbling former home on the island of Vinalhaven, which is listed as a landmark. The artist’s will dictates that the house be turned into a museum dedicated to his life and work that will be run by an independent foundation.