In a wide-ranging interview with PEOPLE, Louis Elizondo tells PEOPLE that the US government has retrieved “non-human” technology and specimens from crashed spacecraft

It’s been seven years since Luis Elizondo began making headlines after resigning from his job as a senior intelligence official for a top-secret Pentagon program that investigated UFO’s — also known as UAP’s or unidentified anomalous phenomena — and going public about his frustration over the lack of transparency on the issue.

The longtime military intelligence veteran spent nearly seven years as director for the Department of Defense’s clandestine Advanced Aerospace Threat Identification Program. What he learned during his tenure convinced him that the countless sightings and encounters with highly advanced aerial phenomena by military pilots and personnel posed a potentially grave threat to our national defense.

Read the rest of Luis’ exclusive interview with PEOPLE here.