NEW YORK, NY.- New York investigators on Wednesday seized three artworks from three out-of-state museums that they said had been stolen from a Jewish art collector killed during the Holocaust and rightly belonged to the Nazi victim’s heirs.

The Manhattan district attorney’s office issued warrants to the Art Institute of Chicago, the Carnegie Museums of Pittsburgh, and the Allen Memorial Art Museum at Oberlin College in Ohio, for works by 1900s Austrian expressionist Egon Schiele. According to the warrants, “there is reasonable cause to believe” that the works constitute stolen property.

Prosecutors say the artworks rightly belong to three living heirs of Fritz Grünbaum, a prominent Jewish art collector and cabaret artist killed at the Dachau concentration camp in Germany in 1941.

The office refused to comment on the seizures, saying they were part of an ongoing investigation into about a dozen Schiele works they say were looted by the Nazis and trafficked at some point through New York. The warrants shift into criminal court a group of Holocaust art recovery cases that were being contested in civil court.

“Whether you are a plaintiff, prosecutor or defense counsel, attorneys are always looking for new precedents,” Mark Vlasic, an adjunct professor of law at Georgetown University and former United Nations war crimes prosecutor, said in an email. “This field of law is shifting so this move will no doubt make some parties quite nervous about how cases are resolved.”

The Schiele works are: “Russian War Prisoner” (1916), a watercolor and pencil on paper piece valued at $1.25 million, which was seized from the Art Institute; “Portrait of a Man” (1917), a pencil on paper drawing valued at $1 million and seized from the Carnegie Museum of Art; and “Girl With Black Hair” (1911), a watercolor and pencil on paper work valued at $1.5 million and taken from Oberlin. The art will be transported to New York at a later date.

In a statement, the Art Institute said: “We are confident in our legal acquisition and lawful possession of this work. The piece is the subject of civil litigation in federal court, where this dispute is being properly litigated and where we are also defending our legal ownership.”

The Carnegie said that it was committed to “acting in accordance with ethical, legal, and professional requirements and norms,” and that it would “of course cooperate fully with inquiries from the relevant authorities.”

The Oberlin museum did not immediately respond to a request for comment.

Before Wednesday’s actions, the Grünbaum heirs had filed civil claims not just against the three museums, but also against the Museum of Modern Art and the Morgan Library and Museum, both in New York City; the Santa Barbara Museum of Art in California; and several individual defendants. The plaintiffs in this case had filed claims seeking the return of other Schiele works at other museums.

In total, the plaintiffs are seeking to recover about a dozen Schiele works once owned by the Austrian-born Grünbaum and now in the United States.

The plaintiffs include Timothy Reif, a judge on the U.S. Court of International Trade; David Fraenkel, a co-trustee of Grünbaum’s estate, and Milos Vavra. One of their main contentions is that Grünbaum, an outspoken critic of German aggression during the 1930s, had been hounded by the Nazis into signing an unlawful power of attorney while at Dachau in 1938. They say he had never ceded rightful ownership of his collection, which was widely and illegally dispersed after the war.

In 2018, the plaintiffs received a favorable judgment with regard to the Nazi “power of attorney” that they hope will serve as a precedent. In the case of Reif v. Nagy in New York County Supreme Court, in which the plaintiffs won back two Schiele works, “Woman in a Black Pinafore” and “Woman Hiding Her Face,” Judge Charles V. Ramos found that “a signature at gunpoint cannot lead to a valid conveyance” of someone’s personal property.

This article originally appeared in The New York Times.