Ever since the Polish-born Jewish revolutionary Rosa Luxemburg was murdered nine decades ago, the fate of her corpse has been a favorite historical mystery for her admirers. (Luxemburg led a brief, failed Communist uprising in Germany in 1919.) Now, thanks to a spit sample from an elderly resident of Jerusalem, the mystery may be solved. A few weeks ago, rummaging through Berlin’s museum of medical history, a pathologist named Michael Tsokos discovered a decapitated, limbless female corpse. He immediately thought of Luxemburg, whose name adorns one of the city’s bustling streets and whose body was never found. Searching online for living relatives of the felled firebrand, Tsokos came across Irene Borde, a great niece of Luxemburg’s who grew up in the Soviet Union and moved to Israel in 1973, settling in Jerusalem. Contacted by Tsokos, Borde agreed to send a spit sample to Berlin, where her DNA will be analyzed and compared with that of the newfound corpse. But the scientist cautioned Luxemburg fans not to get their hopes up: even the most advanced tests cannot indicate a relationship with more than 70 percent certainty.