Thomas Pfaff, a spokesman for Gurlitt's cousin Uta Werner, said Friday she will examine the expert report and has until Feb. 1 to respond. He quoted her lawyers as saying it showed Gurlitt suffered from serious psychological ailments but found no proof that he wasn't competent to write the will.
Gurlitt died in 2014, months after German authorities said they had seized more than 1,000 works at his apartment. He designated a Swiss museum as heir. A lower court rejected Werner's challenge; she appealed.
Both Werner and the museum have promised to ensure any Nazi-looted pieces are returned to Jewish owners' heirs.