SOCORRO.
“On the afternoon of April 24, 1964, Socorro, New Mexico police officer Lonnie Zamora broke off pursuit of a speeding car after seeing a flash of flame and hearing a roar in the desert south of town.”
Zamora called in the sighting in real time, and within minutes Sergeant Sam Chavez of the New Mexico State Police arrived on scene. The two officers found four wedge-shaped landing impressions, charred greasewood plants, and burnt earth at the alleged landing site. The physical evidence was photographed and sampled by the FBI, the US Air Force, and Project Blue Book investigator Hynek, who travelled to Socorro and personally interviewed Zamora.
Project Blue Book listed the Socorro case as officially "unidentified." Hynek wrote that Zamora was "puzzled" rather than excited, struck him as a credible and conservative witness, and that he could find no evidence of a hoax. Astrophysicist James McDonald and later Air Force consultant Ray Stanford both investigated and concluded the physical traces were genuine. The egg-shaped craft was reportedly marked with an insignia that Zamora sketched but which the Air Force asked him to keep confidential.
Skeptical hypotheses have included a Lunar Surveyor lander test from nearby White Sands and a college prank, but no documentation supports either. Zamora maintained his account without alteration until his death in 2009. Socorro is one of a small number of US cases that remain officially unexplained in Blue Book's own records.