Ventura County prosecutors declined to press charges against voice actor Noel Blanc, the pilot in a helicopter carrying actor Kirk Douglas that collided witha stunt plane, killing two people.

Deputy District Attorney Jim Grunert said Wednesday prosecutors were unable to prove that Blanc, son of the late cartoon voice artist Mel Blanc, was grossly negligent in the 1991 accident.

That finding is necessary before a charge of involuntary manslaughter can be filed, Grunert said.