Sergei Gredeskul was a Ukrainian physicist who authored several seminal works on physics of disordered matter — same area my father worked in, so they knew each other pretty well back in the 1970s and 1980s. Sergei got his Sc. D. a few years after my father. In the early 1990s, Sergei and his family moved to Israel, where he taught physics at Ben Gurion University (Be’er Sheva campus). His best-known works from that time described wave propagation in metamaterials — engineered media with properties not found in natural materials (for example, negative refraction index).
During the Hamas incursion into Ofakim, a town about near Be’er Sheva, about 25 km from Gaza, Sergei and his wife Victoria, also a scientist, were killed by Hamas militants. Their bullet-riddled bodies were recently found inside their house. They were 81 years old, retired.