New Jersey-based forensic audio examiner Stuart Allen views the May 4, 1970, shootings at Kent State University as "a murder mystery" and "spy thriller" that he is committed to helping solve.

Allen, along with Alan Canfora, director of the Kent May 4 Center, took the stage at the Kent State Kiva on Tuesday as part of the 41st Annual May 4 Commemoration, which continues today.

The three-hour casual forum had audience members interacting with the men, making comments or asking questions related to the day four Kent State students were killed and nine were injured during 13 seconds of gunfire from Ohio National Guard soldiers.

Allen played for the crowd of about 75 the full half-hour tape recording made on May 4, 1970, by a Kent State student.

Allen promised to take audience members "inside of this tape as the drama unfolds … you’re going to hear sounds that are clearly disturbing."

As the 41-year-old recording played, Canfora presented a slideshow of more than 230 photographs taken that fateful day of antiwar protests. Many – including some Canfora referred to as "gruesome," such as morgue photos of the slain students – have never been published.

After playing the original recording – which Allen said "sounds like mud" – he played digitally "cleaned" portions of the audiotape. His areas of focus included what he said are the sounds of four shots being fired from a .38-caliber pistol just 70 seconds before guardsmen shot their M1 rifles, and a man giving orders to fire mere seconds before the deadly barrage.

Canfora believes that Allen’s revelation of "digital evidence" on the May 4 audiotape, combined with photographic and other overlooked evidence, should prompt the U.S. Justice Department to reopen an investigation into how events unfolded on that historic day.

However, Canfora made a request for evidence review last November and said he’s still waiting for a response from Justice Department officials. He’s preparing to "apply pressure" through personal appeals to state and federal officials, as well as petition drives and letter-writing campaigns.

Canfora said the "May 4 movement for truth and justice" is not about "seeking punishment, retribution or revenge."

"The ultimate outcome we’re seeking is simply the truth … for the sake of history," Canfora said. "The truth provides true healing."

And should the case end up in a court, Canfora said the movement has a "great ally" in Allen. As CEO and chief forensic examiner of The Legal Services Group, Allen has provided expert forensic testimony and evidentiary support in more than 20 federal districts and 40 states for law enforcement and the legal profession.

Allen said he has no financial interest in the outcome of any new May 4 investigation – just a strong desire to find answers to questions created by his digital enhancement of the 1970 audio recording. The biggest questions, he said, are who shot the .38-caliber pistol four times and who gave Guardsmen an order to fire.

"It’s 40 years old and it’s time for closure, to have the truth come out. The issue here is to find out definitively what happened," Allen said.

Since becoming involved with the May 4 movement last year, Allen said he has heard and read many comments along the lines of "let it go, give it up." But he’s not willing to do that. "If it was my kid (killed), I’d never let it go," Allen said as he choked up.

"We need a federal investigation reopened and launched … The evidence is going to speak for them (the slain students)," he said.