Lopez was the guide on the expedition of A.J. Walker.
After Walker gained the trust of the Arumbayan people, they showed him the Heart of the Jungle, an ancient gemstone that the Arumbayas claimed had magical healing powers. Lopez would later steal the gemstone, hiding it in the Idol of the Broken Ear, which, ironically, was a gift given to Walker in gratitude of his vow of silence about the gemstone. The Arumbayas chased Walker's party after learning it was missing. Lopez panicked and fled just before the Arumbayas engaged the expedition, resulting with Walker in possession of the idol, who brought it to Europe. Somehow Lopez' secret ended in a note that Rodrigo Tortilla got in his possession. In The Broken Ear television episode, Lopez's role is substantially enlarged and re-imagined. He completely replaces the character Rodrigo Tortilla as the murdered initial antagonist. Lopez is also featured in the flashback tale of Dr. Ridgewell translating the story of Walker's visit to Tintin as told by the Arumbaya chieftain in the TV adaptation, rather than only being mentioned in the original comic strip.