Paul Roberts, 63, was on duty at the UPS customer care center in Earth City, Missouri, on the night of 4 September when a company vehicle hit him, authorities said.

Roberts, of nearby St Charles, Missouri, died at the scene. The vehicle’s driver cooperated with investigators who responded to reports of the fatal accident, local police said in a statement provided to the Guardian on Thursday.

The federal Occupational Safety and Health Administration (Osha) is investigating Roberts’ death, a process that could take up to six months, an agency spokesperson said in a separate statement on Thursday.

While neither Osha nor the police released more details, Roberts’ story quickly gained attention beyond St Louis because family members told local news media that he had planned to retire on 17 September after 44 years of working at UPS.