I have grave doubts the Colonel actually exists, but only in the mind of Mr Sanchez. Honestly, truly if this Colonel exists would he not be found out considering he is alleging he is still part of a medical team or outfit that works at this military-underground facility! As I said before the Colonel perhaps doesn't exist, and this information (story) was created by Mr Sanchez to sell his book?.. or Mr Sanchez is being spoon feed information from a dubious source who may in fact be a Colonel with the US military ,but that still doesn't neglect the fact Mr Sanchez is being lied to and everything told to him is a lie.
Personally, Mr Sanchez strikes me as being gullible, and a person who may or not or could have been manipulated by the Colonel (whoever he is really?) into spreading information that is false and frequently upon hearing and listening to two hours of this information. I am more than 90 per cent sure the story is fake, and was told to Mr Sanchez for whatever reason, but it was not told to him, so to get this story out to the public and make aware the dangers at the base at Dulce.
Personally, I don't believe their is a underground Alien-non human civilization inside a mountain or underground at Dulce, If such a base existed there. Wouldn't there be clear visible signs of heavily guarded facilities blocked off with fences to stop intrusion by civilians?
Area-51 whatever you believe went on there, still was heavily- patrolled and a large areas of land around and near Area-51 was confiscated by the American Government during the last Fifty years, essentially it was done to keep out Civilians, who were being nosey, and expand the base.
I haven't heard any information were it was claimed people living in the area at Dulce, were asked to move out or asked to avoid going into certain areas for their own safety. Honestly knowing what we do know about other TOP-SECRET bases scattered around the United states, is it feasible Dulce would have such low security if any part of the story convened to us the audience was true?
The whole Story about the Non Humans in the caverns, sounds made up. If we truly have Visitors coming to the planet since the dawn of time, I don't believe the story we heard here is an accurate time-line-history of visitation to our planet.