Frederick Cox, 30, of Trotwood, faces three counts of murder, along with felonious assault charges.
Prosecutors say Cox went into the plant on Dryden Road where he worked on May 18 and shot two people.
Jeffrey James Allen III, 28, died after being shot at least a dozen times, according to authorities.
Several witnesses identified Cox who left the building and shot himself in the head. Cox was released from the hospital last week, and he was taken into custody at that time.
Cox is being held on $1 million bond and is scheduled to be arraigned Thursday morning.