CLEVELAND (AP) -- The U.S. Justice Department won't reopen its investigation into the deadly 1970 shootings by Ohio National Guardsmen during a Vietnam War protest at Kent State University.

A letter from an assistant attorney general says there are multiple legal hurdles to further prosecuting the case.

The letter was addressed to Alan Canfora, who requested that the investigation be reopened. He was among the wounded students and now directs the Kent May 4 Center.

The letter says a government review was inconclusive in determining whether a newly enhanced audio recording of the shooting provided evidence of extra gunfire and someone ordering people to fire on students.

Four Kent State students died, and nine were hurt.

Canfora tells The Plain Dealer in Cleveland ( http://bit.ly/IdGYet ) the government's decision is disappointing but not surprising.

---

Information from: The Plain Dealer, http://www.cleveland.com