berlin german police launch investigation theft least 12 inscribe metal memorial stone embed pavement berlin commemorate nazi victims stone call stolpersteine bear name victims set grind front last address live murder detain wartime regime upset hurt cologne artist guenter demnig say tuesday day thefts make public demnig say 600 stone steal total 63,000 lay across europe since launch project 1996. police say clear behind thefts though local politician blame members far right link action approach anniversary 1938 kristallnacht pogrom jews germany austria similar theft eastern city greifswald four years ago also take place eve anniversary attack government-backed mob loot jewish property set fire kill dozens jews someone make effort remove systematically pick stone political motives say spokesman berlin politician fritz felgentreu point say strong far-right presence neighborhood thefts take place nazi victim memorial stone steal berlin police probe