Question: When should the Goldwasser and Regev families sit shivah for their murdered son/brother/husband? It could be two years since their deaths, but it was only confirmed today…
Answer: That is a good question, although it is tragic that it must be answered practically and not just hypothetically. Shivah always begins after the burial. If a close relative did not hear of the death and burial, then the mourning period for that person would start at the time that he heard the bad news. It seems to me that, in this particular case, the two will coincide. However, if not, mourning will start after the burial.
If, G-d forbid, this question has practical relevance to an individual in the future, he or she should speak to a competent authority in Jewish law for details.
Best wishes,
Rabbi Azriel Schreiber