It also turned out that the FBI had its own informant and agent-provocateur roaming the crowd, a part-time Kent State student named Terry Norman, who had a camera. Mr. Norman also was armed with a snub-nosed revolver that FBI ballistics tests, first declassified in 1977, concluded had indeed been discharged on that day.

Then there was the testimony of an ROTC cadet whose identity remains unknown, one of the pervasive redactions concealing the names of all the FBI agents who conducted the interviews and of all those whom they interrogated. Although presumably angry over the demonstrators’ destruction of the campus ROTC building, the cadet’s calm, precise firsthand account nonetheless carries a credibility not easily dismissed.

Before the fatal volley, the ROTC cadet told the FBI, he “heard one round, a pause, two rounds, and then the M-1s opened up.”

The report continued that the cadet “stated that the first three rounds were definitely not M-1s. He said they could possibly have been a .45 caliber. … [He] further stated that he heard confirmed reports of sniper fire coming in over both the National Guard radio and the state police radio.”

The cadet also told the FBI he observed demonstrators carrying baseball bats, golf clubs and improvised weapons, including pieces of steel wire cut into footlong sections, along with radios and other electronic devices “used to monitor the police and Guard wavelengths.”

Separately, a female student told the FBI she “recalled hearing what she thought was [the sound of] firecrackers and then a few seconds later [she] heard noise that to her sounded like a machine gun going off, but then later thought it may have been a volley of shots from the Guard.”

Absent the declassification of the FBI’s entire investigative file, many questions remain unanswered — including why the documents quoted here were overlooked, or discounted, in the Justice Department’s official findings.