Now, my dear, if you´ve answered all questions correctly, then there should be just two remaining suspects.
Now add all the numbers of the symphonies and string quartets you will find in the character descriptions of Tibor Dalasc, Rainhardt Sonnenblum and Giuseppe Quindici, eg.: Nr. 47 + Nr. 15 + ? and so on…
Subtract Jo’s age (77) from the sum you’ve calculated before. You will finally get a number that resembles the amount of letters of the first name of a famous dancer who was a descent of Eisenstadt.
Her dad could by no means be the thief of the opera!
…the name of the evildoer is?