Another thread inspired me to read up on this. I remember when it happened. It was tragic... shocking... I was a pup. I read Wiki and was surprised by this snippet :

"In 2007 Alan Canfora, one of the wounded, located a copy of a tape of the shootings in a library archive. The original 30-minute reel-to-reel tape was made by Terry Strubbe, a Kent State communications student who turned on his recorder and put its microphone in his dorm window overlooking the campus. A 2010 audio analysis of a tape recording of the incident by Stuart Allen and Tom Owen, who were described by the Cleveland Plain Dealer as "nationally respected forensic audio experts," concluded that the guardsmen were given an order to fire. It is the only known recording to capture the events leading up to the shootings. According to the Plain Dealer description of the enhanced recording, a male voice yells "Guard!" Several seconds pass. Then, "All right, prepare to fire!" "Get down!," someone shouts urgently, presumably in the crowd. Finally, "Guard! . . . " followed two seconds later by a long, booming volley of gunshots. The entire spoken sequence lasts 17 seconds. Further analysis of the audiotape revealed that four pistol shots and a violent confrontation occurred approximately 70 seconds before the National Guard opened fire. According to The Plain Dealer, this new analysis raised questions about the role of Terry Norman, a Kent State student who was an FBI informant and known to be carrying a pistol during the disturbance. Alan Canfora said it was premature to reach any conclusions.[50][51]

In April 2012 the United States Department of Justice determined that there were "insurmountable legal and evidentiary barriers" to reopening the case. Also in 2012 the F.B.I. concluded the Strubbe tape was inconclusive because what has been described as pistol shots may have been slamming doors and that voices heard were unintelligible. Despite this, organizations of survivors and current Kent State students continue to believe the Strubbe tape proves the Guardsmen were given a military order to fire and are petitioning State of Ohio and U.S. Government officials to reopen the case using independent analysis. The organizations do not desire to prosecute or sue individual guardsmen believing they are also victims.[52]["