The uncle of Juan Guaido was arrested on charges of smuggling explosive material onto an airline on Friday.
Juan Jose Marquez was arrested on his return to Venezuela after aiding his nephew on an international tour.
Officials at the US State Department decribed his guilt as unlikely, saying that the events that preceded the arrest show that Marquez went through detailed security screenings in Lisbon, Portugal before the flight and nothing was found, suggesting that it was unlikely that Marquez was intentionally smuggling explosive material.
Officials also suggested that the arrest is politically motivated, put in action by the opposition party, the current Maduro regime.
There is a political battle over leadership inside Venezuela since it was announced that Juan Guaido would be recognized as president over Maduro last year.
President Maduro presided over an economic collapse that resulted in mass flight from the country, in which 5 million people left during economic hardships, causing a migration crisis in South America. Maduro's dictator-like actions prompted mass protests and political upheaval. Guaido, an opposition party leader, assumed leadership of the country unofficially, with public support divided.
The United States, along with 49 other countries recognize Guaido as the president of Venezuela, though Maduro officially maintains the title inside Venezuela, refusing to relenquish his place.