The Coyame incident
The account
An object collided with a small plane over the desert, and an American team supposedly crossed the border to haul away the wreckage.
What investigators found
There is no official record of the collision or the operation; the story comes from an anonymous document of unproven origin.
The story
According to this story, in August 1974 radar picked up an object coming from the Gulf of Mexico and heading north. Over the Chihuahua desert, near Coyame, it supposedly collided with a small civilian plane. Mexican teams reached the site, and shortly afterward an American unit allegedly entered the country by helicopter to recover the craft without leaving a trace.
The account gained traction in the 1990s, based on an anonymous text presented as a secret report. No government confirmed the episode, and the names, times and equipment it mentions were never verified in any archive. The case became known as the "Mexican Roswell," but it still lacks any independent evidence.