Have you heard of Pavel Haas? Probably not. If you are interested in Czech music, you should czech him out :-) He was a composer, sent to Theresienstadt concentration camp for being Jewish. He was a student of Leos Janacek. He was murdered in Auschwitz on the orders of the notorious Josef Mengele.
You may read more about him here.
You may listen to some of his music here.