An audiocassette that has sat in a Yale library for nearly two decades may hold the evidence explaining why Ohio National Guard troops shot into a crowd of war protesters at Kent State University in 1970.

The recording, made public this week by a victim of the shooting, seems to capture the sound of someone ordering the Guardsmen to fire on students protesting the Vietnam War, killing four and wounding nine. Now, 33 years after eight of the Guardsmen were acquitted of any wrongdoing, some survivors of the shooting are calling for the investigation of the case to be reopened in light of the new evidence.

The Yale University Library’s Manuscripts and Archives department provided a copy of the recording to a reporter on Tuesday, about an hour before copies of the tape were released by Alan Canfora at a press conference on the Kent State campus. Canfora, who was shot in the wrist during the protest, now heads a non-profit organization that commemorates the incident.

Just before gunfire rings out on the tape, a barely audible male voice can be heard ordering what seems to be, “Right here! Get set! Point! Fire!” Immediately after that last command, a hail of gunfire breaks out, lasting for 13 seconds.

That voice, Canfora alleges, belongs to a Guard officer issuing orders for his troops to fire on the crowd.

“I was very stunned when I heard the recording,” Canfora said Wednesday. “I think this tape recording clearly destroys the cover-up.”

Amid static and shouting from the crowd, the sequence of commands is barely audible to a casual listener — and even at close examination, it is debatable whether the voice orders “Right here” or “Over here,” for instance. But such is the case with most of the tape: with static and claps and chants from the crowd of students, along with a nearly constantly-ringing alarm bell and the drone of a helicopter or aircraft overhead, much of the chatter on the tape is difficult to discern.

But some students’ comments before the gunshots began are eerie harbingers of what was to come. Fifteen minutes before the shooting, the voices of police or Guard troops on the scene can be heard ordering students to leave the area immediately for their own safety, to which a student responds, with a laugh, “They’re going to shoot ‘em!”

Two minutes later, an observer describes the National Guard soldiers moving toward the crowd, “with their rifles in air.”

“The crowd ain’t moving, folks,” someone says. The protesters, a voice says, are going to “stand ’til the bitter end.”

The 26-minute tape was recorded by Kent State student Terry Strubbe, who placed a microphone on his dorm room windowsill during the demonstrations and switched on his reel-to-reel tape recorder. Strubbe has kept that original tape in a safe-deposit box since the incident, but Canfora said he learned that the University had a copy in its archives while browsing the contents of the Kent State Collection on the Yale Library’s Web site about six months ago.

For $10, Canfora said, he ordered a CD of the recording, which is the only known account of the full 13 seconds of shooting. It was difficult enough listening to the tape knowing that the shootings were minutes and seconds away, Canfora said, but when he heard what he believes to be an order to fire and the 67 gunshots that followed, he cried.

The tape is one of more than 25 audio recordings that are included in the University’s extensive archive of the Kent State shootings. This specific tape is part of a 62-box collection of court documents and other materials from the records of David E. Engdahl, the attorney who led a civil suit on behalf of the victims of the shootings. The trial and other related cases progressed from 1970 to 1981, and Manuscripts and Archives received the records in 1989, according to the department’s description of the collection.

While it might seem strange that Yale’s library system would have such an extensive collection of primary documents relating to an incident decidedly unrelated to Yale, such is the case with many of the University’s collections, said Cynthia Ostroff, Manuscripts and Archives’ public services manager. In this case, someone involved in the Kent State incident and its aftermath had a tie to Yale and suggested the University as a secure place to safeguard the records of the shootings and to ensure that they would always be open to researchers, she said.

“They didn’t want to give all the papers and information to Kent State,” Ostroff said.

And while most Yale students may not know about Yale’s extensive collection of records and documents related to the tragedy, it has proved helpful to Kristine Berzins ’08, who is writing about one of the Kent State victims in a 20-page paper for a history seminar.

For her paper, Berzins said, she has reviewed only about two boxes of records in the collection and never came across the audiotape. Given the amount of materials the University has about the shootings as well as the lengthy litigation that followed, it should not be much of a surprise that the tape took this long to surface, she said.

“It would take months just to look at it all,” Berzins said. “There’s so much in the archives that could be uncovered … I haven’t even scratched the surface.”

But now that the tape has been discovered, Canfora said he and other survivors of the incident and their families are calling for the investigation of the incident to be reopened. They plan to bring the new evidence to the attention of the U.S. Justice Department, as well as members of Congress and Ohio’s attorney general, Canfora said.

Still, some remain skeptical about Canfora’s claims. Officials at Cambridge-based BBN Technologies, which was contracted by the Justice Department to analyze the gunshots on the tape during the 1970s litigation, have told reporters that they believe no Guardsmen’s voices were audible on the tape and that none could be present because the troops were too far away from the microphone to be recorded. And one former Guardsman who fired on the students, Larry Shafer, told the Kent-Ravenna Record-Courier on Tuesday that he never heard any command to fire and that “Point!” would not have been part of a proper command anyway.

Later in 1970, a report issued by the President’s Commission on Campus Unrest concluded only that “the events which occurred as the Guard … turned and fired on the students are in bitter dispute.” Friday is the 37th anniversary of the shootings, which occurred after four days of protests over the United States’ invasion of Cambodia during the Vietnam War.