Bernardo Gruber was a German peddler who traveled El Camino Real up from Mexico City to the Spanish outposts along the middle Rio Grande in Nuevo Mexico. He was also, apparently, a pow-wow man and got himself in trouble with the Spanish Inquisition.

During Christmas Mass in 1668, Gruber and an associate, Juan Serrano, entered the choir loft of the church at Quarai Pueblo, to advertise a new product. (Salinas National Monument, southeast of Albuquerque, preserves the ruins of Quarai and Abo Pueblos).

They reportedly whispered to the chorus members, "He who eats one of these slips of paper, will, from that hour of this first day to that same hour of the second day, be free from any harm, whether it be caused by knife or shot". On these papers was written "X A.B.V.A. X A.D.A.V. X" or "X ABNA X AKNA X" (Different documentary sources provide different sets of letters.) Neither Gruber nor members of the Inquisition tribunal who examined the case in 1670 had any idea what the charms meant, but they are typical of “magic squares” used in German folk magic. The good folk of Quarai tested Gruber's charm, and found it worked: Juan Nieto, who had eaten one of the papers was pricked with an awl and then a knife yet remained uninjured. Nieto, however, repented of his superstitous ways and turned Gruber over to the Inquisition.

Gruber was imprisoned on a rancho near Sandia Pueblo (later the site of the city of Albuquerque) for two years. Gruber escaped his captivity, only to be killed by Apaches while fleeing back to Sonora. The place on the trail, south of Socorro, where Gruber’s body was found came to be known as “Jornado del Muerte” (Dead Man’s Route).

In 1945, this remote and desolate place was code-named “Trinity” and used to detonate the first atomic bomb.

Sánchez, Joseph P., "Bernardo Gruber and the New Mexico Inquisition, 1668-1671." (1996)