"Ohio"

Tin soldiers and Nixon coming,
We're finally on our own.
This summer I hear the drumming,
Four dead in Ohio.

Gotta get down to it
Soldiers are cutting us down
Should have been done long ago.
What if you knew her
And found her dead on the ground
How can you run when you know?

On the eve of the 42nd anniversary of the shootings, four students wounded that day asked U.S. Attorney General Eric Holder to investigate digitally enhanced audio evidence they believe proves an officer ordered the guardsmen to fire on the unarmed students.

A command to fire has never been proven and guardsmen said they fired in self-defense. Criminal charges were brought against eight guardsmen, but a judge dismissed the case. Wounded students and families of those slain later received a total of $675,000 after civil lawsuits.

The shootings also spawned an investigative commission, numerous books and Neil Young's song, "Ohio," which became an anti-war anthem. A Pulitzer Prize-winning photograph of a teenage girl kneeling over the body of one of the slain students became an enduring image of the tragedy.

In 2010, Alan Canfora, one of the wounded students and director of the nonprofit Kent May 4 Center, asked the Justice Department to review the enhanced recording, which was taken 250 feet from the guardsmen when they fired their shots in 1970.