Proof
"This is…" The people were shocked when the doctor opened the kid's body. There wasn't a single bone or organ inside. There was only red liquid like blood, but it didn't seem to be blood.
But to their surprise, when they checked the red liquid, it was concluded to be blood. Even the machine said the same thing. And the worst part was the fact that this was a human's blood, except for the fact that it shouldn't have belonged to the same person.
"What? The DNA in their blood and their skin cells are different?"
"Then, no human interior features and blood belong to a different body… With all these facts, they are truly monsters."
"In that case, what kind of monster are they?"
The people were confused. They had just experienced a huge war and now they had to take care of the infiltration.
"How many monsters have entered this base?"
"Not good. We have to lock up the entire facility. We need to make sure those monsters can't spread even more."