BUDAPEST, Hungary (AP) — During World War II, within the walls of the Nazi concentration camp at Dachau, a Jewish prisoner secretly penned a short note and hid it inside a violin he had crafted under harrowing circumstances — a message to the future that would remain undiscovered for more than 80 years.

“Trial instrument, made under difficult conditions with no tools and materials,” the worn note read. “Dachau. Anno 1941, Franciszek Kempa.”

The origins of the violin, built in 1941 by Franciszek “Franz” Kempa while imprisoned by the Nazis at Dachau in southern Germany, remained unnoticed for decades. It wasn’t until art dealers in Hungary sent the instrument out for repairs — after having stored it for years among a set of purchased furniture — that its history came to light.

Although the instrument’s craftsmanship pointed clearly to a skilled maker, the professional repairing it was puzzled by the poor quality of the wood and the crude tools used to create it, which didn’t match the evident skill involved.

“If you look at its proportions and structure, you can see that it’s a master violin, made by a man who was proficient in his craft,” said Szandra Katona, one of the Hungarian art dealers who discovered the origins of the violin. “But the choice of wood was completely incomprehensible.”

Motivated by the contradiction, the professional disassembled the violin, revealing Kempa’s hidden note — an apparent explanation, even an apology, from a master violin maker forced by the brutal limitations of his captivity to build an instrument that fell short of his own standards.

Dachau, located near Munich, was the first concentration camp established by the Nazis in March 1933. It initially housed political prisoners but later became a model for other camps, imprisoning Jews, Roma, clergy, homosexuals, and others targeted by the Nazi regime.

Over time, it became a site of forced labor, medical experiments, and brutal punishment, and remained in operation until it was liberated by American forces on April 29, 1945. At least 40,000 people are believed to have died there due to starvation, disease, execution, or mistreatment.

There is ample evidence that musical instruments were present in concentration camps across Central and Eastern Europe during World War II. For propaganda purposes, the Nazis often permitted or even encouraged the formation of musical groups to give a false impression to the outside world about life in the camps.

However, all known instruments that survived Dachau are believed to have been brought in by prisoners. Kempa’s “violin of hope,” as it has come to be called, is the only known instrument actually built inside the camp.

It is unknown how the violin left Dachau and ultimately made its way to Hungary. But Kempa, according to documents provided to the Hungarian art dealers by the museum at the Dachau memorial site, survived the war and returned to his native Poland to continue making instruments before dying in 1953.

The documents also suggest that Kempa was known to the Nazis as an instrument maker — something Tamás Tálosi, one of the art dealers, believes may have spared him the fate of millions of others that perished in the camps.

“We named it the ‘violin of hope’ because if someone ends up in a difficult situation, having a task or a challenge helps them get through a lot of things,” Tálosi said. “You focus not on the problem, but on the task itself, and I think this helped the maker of this instrument to survive the concentration camp.”