The Lead Masks Case was the name given to the events which led to the death of two Brazilian electronic technicians: Manoel Pereira da Cruz and Miguel José Viana. Their bodies were discovered on August 20, 1966.
On August 20, 1966, a Saturday,
Two men were found dead on the hill of the Penny in Santa Rosa neighborhood, in Niterói, State of Rio de Janeiro.
No sign of violence or fighting. The bodies were coming, one after the other, lying on his back, upon a kind of "bed" made of sheets of Pintoba, a species of palm, which were cut with a knife or something similar. The bodies were dressed in suits clean and raincoats.
The bodies were already in an advanced state of putrefaction. On the side of a strange body of cement in March, a magnesian mineral water, a sheet of foil that was used as a drinking cup, a wrapping paper with two towels, a pair of glasses with a black ring in a stem, a handkerchief with the initials "MAS", two shades of crude lead, a paper with basic equations of electron and a strange writing paper.
No obvious injuries were discovered at autopsy; however, a search for toxic substances was impossible as the internal organs of the two victims were not properly preserved.
The case was mentioned prominently (among other Brazilian cases) in Jacques Vallée's book Confrontations.