A musical manuscript handwritten by Ludwig van Beethoven is getting returned to the heirs of the richest family in pre-World War II Czechoslovakia, whose members had to flee the country to escape the Holocaust.

The Moravian Museum in the Czech city of Brno has had the original manuscript for the fourth movement of Beethoven’s String Quartet n B-flat Major, Op. 130 in its collection for more than 80 years. The museum put the score on display for the first time in anticipation of handing it over to its rightful owners.

“It’s one of the most precious items in our collections,” museum curator Simona Sindelarova said.

The museum said a restitution law on property stolen by German Nazis made the return possible. Details about how the family, whose wealth came mainly from mining industry and banking in Central Europe, after World War I acquired the piece from one of the German composer’s late quartets is unknown.

“We’re sorry about losing it, but it rightly belongs to the Petschek family,” Sindelarova said.

Beethoven composed the six-movement String Quartet in B-flat Major in 1825-26 as part of his work on a series of quartets commissioned by Russian Prince Nicholas Galitzin. It premiered in March 1826 at the Musikverein concert hall in Vienna, Austria.