The small skeletons, about 60cm long, prompted a bizarre break in proceedings last week as Jaime Maussan presented them in large wooden caskets to lawmakers.
Maussan claims that the bodies were found in Peru and are “non-human beings that are not part of our terrestrial evolution”.
However, scientists and academics have dismissed the discoveries as yet another stunt by Maussan in his quest to prove the existence of aliens.
Doctors at a laboratory in Mexico City did X-rays and CT scans of the bodies on Tuesday.
Jose de Jesus Zalce Benitez, the director of the Health Sciences Research Institute of the Secretary of the Navy, which did the tests, said they showed the bodies had not been assembled or manipulated.
That contradicted earlier suggestions that the bodies had been assembled with animal or human bones - though is unlikely to assuage Maussan’s critics because of his relationship with Benitez. The pair appeared alongside each other at the Mexican congress to give evidence of their discoveries.
Previous claims made by Jaime Maussan have been discredited. Photo / Getty Images
“[They] belong to a single skeleton that has not been joined to other pieces,” he said.
Benitez, who previously claimed “these bodies have no relation to human beings,” also made claims about large lumps inside the abdomen of one of the bodies.
He said scans by his team showed one “was alive, was intact, was biological and was in gestation”, suggesting the lumps could be eggs.
Footage of the team doing the tests shows one of the bodies had an elongated head, two slanted eyes and a small upturned nose. While it bears a resemblance to fictional depictions of aliens, scientists have yet to suggest that they are indeed from another planet.
One theory put forward by academics and archaeologists is that the remains are mummified human bodies.
The Peruvian government has said they are pre-Hispanic objects, with officials there saying that they have begun a criminal probe into how the bodies left the country.
One of the two 'non-human' beings displayed to the media is seen during a press conference of Mexican journalist Jaime Maussan. Photo / Getty Images
The bodies, which have three fingers on each hand, were recovered in Peru in 2017. Photo / Getty Images
Maussan, 70, has said he is innocent and has done “absolutely nothing illegal”.
However, Maussan could not explain how the corpses came into his possession and has a history of peddling discredited narratives around aliens.
He appeared in a 2017 TV documentary about other remains found near the Nazca Lines, which experts have said appeared to feature doctored mummies.
Of his recent finds, he said he would reveal all “at an appropriate time”.
Dan Evans, an assistant deputy associate administrator for research at Nasa, said this week: “Our primary goal today is to steer away from speculation and conspiracy theories and towards a scientific and rational approach, and this is achieved through rigorous data analysis”.