http://en.wikipedia.org/wiki/Kent_State_shootings#Casualties
Eight of the guardsmen were indicted by a grand jury. The guardsmen claimed to have fired in self-defense, a claim that was generally accepted by the criminal justice system. In 1974 U.S. District Judge Frank Battisti dismissed charges against all eight on the basis that the prosecution's case was too weak to warrant a trial.
Civil actions were also attempted against the guardsmen, the State of Ohio, and the president of Kent State. The federal court civil action for wrongful death and injury, brought by the victims and their families against Governor Rhodes, the President of Kent State, and the National Guardsmen, resulted in unanimous verdicts for all defendants on all claims after an eleven-week trial.[48] The judgment on those verdicts was reversed by the Court of Appeals for the Sixth Circuit on the ground that the federal trial judge had mishandled an out-of-court threat against a juror.
In the succeeding years, many in the anti-war movement have referred to the shootings as "murders," although no criminal convictions were obtained against any National Guardsman. In December 1970, journalist I. F. Stone wrote the following:
To those who think murder is too strong a word, one may recall that even Agnew three days after the Kent State shootings used the word in an interview on the David Frost show in Los Angeles. Agnew admitted in response to a question that what happened at Kent State was murder, "but not first degree" since there was as Agnew explained from his own training as a lawyer "no premeditation but simply an over-response in the heat of anger that results in a killing; it's a murder. It's not premeditated and it certainly can't be condoned."