Rigo was born in 1955 in Czechoslovakia, of Roma family, and grew up in institutions. He worked intermittently and travelled between Bratislava and western Europe on tourist papers in the period immediately after the borders opened.
Between June 1990 and 1992 he killed nine people. Helena S., forty, and Ilka Z., twenty-eight, in Munich; Maria van der W., fifty-eight, in Amsterdam; Terezia R., eighty-eight, and Anna P., forty, and her teenage son, in Bratislava; and others in Slovakia. He entered flats at night, usually through a window, and beat the sleeping occupant about the head with a metal bar, a stick or a stone. Several of the bodies were sexually interfered with after death, and he took small items. European reporting called him the International Killer, for the countries he moved through, and the Sock Killer, after what he used.
That the series ran across three countries in the first years after 1989, before there was any working exchange of criminal intelligence between them, is why it lasted as long as it did; the German, Dutch and Slovak cases were not connected until he was arrested in Bratislava in 1992.
He was tried in Slovakia, convicted of nine murders, and sentenced to life imprisonment, the first life sentence handed down in independent Slovakia. He remains in custody. The German and Dutch cases were resolved administratively against him rather than tried separately.