After the reports were attributed to swamp gas by Air Force civilian investigator J. Allen Hynek, the explanation was widely derided.

[4] For nearly three hours, beginning around 3:50 a.m. on March 14,[5][better source needed] Washtenaw County residents, sheriffs and police reported witnessing lights in the sky moving at high speeds over Lima Township.

[7][8][9] From 3 to 7 A.M. on March 16, Washtenaw county Sheriff's Deputy David Fitzpatrick and his partner Neul K. Schneider saw two lights in the skies over Milan.

[10] On March 20, 1966, Frank Mannor, his wife, and teenage son Ronald were home at their farmhouse northwest of Dexter, watching television.

[11] Around 8:30 p.m., alerted by the noise of their six farmdogs, Mannor reported seeing a red "falling star" to the north which then hovered above a nearby marshy area while emitting light.

[16] They called William Van Horn, Hillsdale County civil defense director, who investigated and observed the lights through binoculars.

Hillsdale police officers Harold Hess and Jerry Wise observed the object and reported radio damage after the event.

[19][20] On March 22 residents of Dexter and Hillsdale continued to report flying objects, strange sounds, and unexplained lights.

[21][better source needed] On 6:15PM on March 24, Robert Nichols and his wife phoned Holland police to report an object flew across a highway at a height of 200 ft (61 m).

[26] Papers covered a variety of speculations, including one from and unnamed self-described 'expert' in California who believed "the UFO was filling up on swamp water to recharge its batteries".

[31] Sheriff of Washtenaw County Douglas Harvey recalled driving Hynek to the Mannor's farm where they witnessed circular marks in the vegetation at the supposedly landing site.

[33] At the conference, attended by sixty members of the press, Hynek credited "marsh gas" as causing the Dexter and Hillsdale sightings.

[39] On March 28, Hynek's swamp gas theory prompted then-Michigan Congressman (and future president) Gerald R. Ford to call for a thorough Congressional investigation of "the rash of reported sightings of unidentified flying objects in southern Michigan".

[11][45] On April 6, Hynek testified before the House Armed Services Committee alongside Air Force Secretary Harold Brown and Bluebook chief Major Hector Quintanilla.

[37] Reading a statement 'certainly not dictated by the Air Force', Hynek broke with organization and suggested some aspects of UFOs merited serious study.

[46][better source needed] In 1966, Congress heard testimony from James Ferguson that the sightings were under investigation by the Aerial Phenomena Branch of the Foreign Technology Division at Wright Field.

[48][49] Alan Hynek, the Air Force UFO expert who popularized the swamp gas hypothesis later argued the topic merited serious study.

In 1968 testimony before a House committee, Hynek recalled "I do not feel that I can be labeled a flying saucer 'believer'-my swamp gas record in the Michigan UFO melee should suffice to quash any such ideas".

[3] In 2019, a TV series loosely inspired by Hynek's life dramatized a public rejection of his swamp gas hypothesis.

"the sightings were so widespread and the witnesses were so credible that law enforcement and senators and governors and faculty researchers would all become involved trying to figure out what in the world was going on.