A 67-year-old man died after what is believed to be the accidental mixing of cleaning chemicals at a manufacturing site in Beatrice, a city in Nebraska.
The man was a resident of Mosaic, a faith-based centre which aims to help people with mental disabilities into employment, according to the Beatrice Daily Sun newspaper.
Michael Robertson, 67, was cleaning at the factory on December 12 under the supervision of Mosaic staff when two workers became ill.
Mosaic is a faith-based organization that aims to pair individuals with intellectual disabilities with meaningful employment.
Beatrice Fire and Rescue Chief Brian Daake said authorities may never know what caused the incident, but speculated it could have been an accidental mixture of cleaning supplies.