From The Place Names of New Mexico, Robert Julyan:
Sierra Ladrones, Spanish “thieves mountains'” named because Navajo and Apache raiders of the settlement long the Rio Abajo would take stolen stock here, safe from pursuit in the mountains’ steep and treacherous canyons. Later, non-Indian rustlers and highwaymen used these rugged mountains as a hideout, and legends abound of treasure still hidden here. Often called simply Los Ladrones. Highest elevation, 9,210; Ladron Peak is 9,143ft.
The Ladrones is a nice long day trip and even better for car camping if you’re prepared. The road tends to be rocky, not muddy. [keep reading]