The chief prosecutor in the southern city of Augsburg, who is investigating 80-year-old Cornelius Gurlitt on charges including tax evasion, acknowledged that some of the more than 1,400 works confiscated from his home in February 2012 clearly belonged to him. More than 400 of the paintings could be returned to Gurlitt.
"It is of key importance that works taken in connection with Nazi persecution be identified so that outstanding property claims can be settled and possible previous owners can exercise their rights," prosecutor Reinhard Nemetz said in a statement.
"At the same time, determining the provenance of the paintings also makes possible an identification of those artworks that without a doubt belong to the accused, whose return should be immediately offered to him," he added.
Nemetz said he had asked a task force appointed last week to identify such paintings "as soon as possible".
Gurlitt is the heir of a powerful art dealer tasked by the Nazis with selling works that they stole, extorted or seized in exchange for hard currency, and with handpicking masterpieces for a "Führer Museum" for Adolf Hitler in the Austrian city of Linz that was never built.
The task force said last week that of the 1,406 long-lost paintings,sketches and prints seized at Gurlitt's Munich flat, about 970 were suspected of being looted from Jewish families or taken from museums in a crackdown on avant-garde, "degenerate" art.
Untangling the ownership of the works by the likes of Picasso, Matisse,Chagall, Renoir and Delacroix is expected to be a drawn-out process, complicated by Gurlitt's insistence that he will not give up the works without a fight.
"I will not give anything back voluntarily," a defiant Gurlitt told this week's Der Spiegel magazine.