CNN  — 

During a ceremony and press conference Wednesday in New York, seven drawings by the Austrian expressionist Egon Schiele were returned to the heirs of their former owner, Fritz Grünbaum, whose art collection was stolen by the Nazis during World War II.

The early 20th century works were all “voluntarily surrendered” by the institutions and collectors that held them after Manhattan District Attorney’s Office’s Trafficking Antiquities unit presented evidence that they had been stolen, District Attorney Alvin Bragg, Jr. said in a statement.

Fritz Grünbaum was a Jewish Austrian cabaret performer whose work “defined cultural life” in 1930s Vienna, according to the Holocaust research project Music and the Holocaust. His routines, which often openly derided Nazism and Hitler, were eventually banned, and Nazis arrested Grünbaum in 1938. His wife, Elisabeth, was later forced to turn over her husband’s art collection — which Bragg said Wednesday included “hundreds of pieces” — to the Nazis.

Grünbaum was imprisoned at Dachau, a concentration camp in southern Germany, where he died in January 1941. Elisabeth died at a concentration camp in Minsk, Belarus, the following year, said Timothy Reif, one of Grünbaum’s heirs, at Wednesday’s ceremony.

“I hope this moment can serve as a reminder that despite the horrific death and destruction caused by the Nazis, it is never too late to recover some of what we lost, honor the victims, and reflect on how their families are still impacted to this day,” Bragg said in a statement. “We still have so much to learn from Fritz Grünbaum and these seven pieces that he found to be so beautiful.”

The 81 pieces Grünbaum collected from Schiele, who completed much of his work in the few years before his death in 1918 at just 28, were primarily self-portraits or drawings of Schiele’s wife, Edith. Grünbaum’s collection included “I Love Antithesis,” a colorful watercolor painting of the artist, and “Girl Putting on Shoe,” which was previously held by MoMA.

Schiele’s drawings were deemed “degenerate” by the Nazi party — a term they used to describe works of modern art they’d decided could “endanger public security and order,” per the US Holocaust Memorial Museum. Nazi officials looted countless pieces of “degenerate” artwork from museums, galleries and private owners during World War II, in part to help fund the party; many have since ended up being displayed in prestigious galleries and museums around the world.

Advocates have for decades attempted to identify the owners from whom the artworks were stolen. In the case of Grünbaum’s Schiele collection, the works changed hands repeatedly after they were seized and sold by the Nazis, ending up for sale at one point by a Swiss auction house and later in the collection of a New York-based gallerist in the mid-1950s, who sold them again, Bragg said. Before they were returned to Grünbaum’s heirs, the works were last held by MoMA, the Morgan Library, the Ronald Lauder Collection and the Vally Sabarsky Trust in New York, as well as the Santa Barbara Museum of Art in California.

Earlier this week, additional Schiele pieces were “seized” from three US museums amid other efforts to reunite Grünbaum’s collection, though they currently remain at the museums pending further investigation.

At least six of the returned Schiele works will be sold at auction to fund the Grünbaum Fischer Foundation, a scholarship program for young musicians, said Reif, whose paternal grandfather was Grünbaum’s first cousin, in an interview with the New York Times.

“Your recovery of these artworks reminds us once again that history’s largest mass murder has too long concealed history’s greatest robbery,” Reif said at Wednesday’s ceremony. “Remembering (the Grünbaums’) lives defeats Hitler’s plan to erase this brave Jewish man’s name from the book of history.”