The pedestrian died after being hit by a large bucket loader at the UPM plant in Shotton, at 11:30 GMT on Monday.
The case has now been handed over to the Health and Safety Executive (HSE) for sole investigation.
UPM Shotton general manager David Ingham said: "We are all deeply shocked by this tragic incident."
The man who died was a contract worker in the inbound recovered fibre warehouse, where the bucket loader is used to move waste paper from the floor to the recycling lines.
The HSE has interviewed witnesses and reviewed materials relating to the incident.
A man arrested in connection with a death at a Flintshire paper mill has been released without charge, North Wales Police has said.