SMITHTOWN - Investigators are trying to figure out why a worker fell into a sewage vat and died at an apartment complex in Smithtown.

The medical examiner will conduct an autopsy to figure out what caused the worker at the Avalon Commons apartment complex to fall in. Richard Dennison, 43, did not come home from work last night, so his wife called his employer, United Cesspool Service. Cops say the company then called 911 when it found out Dennison had fallen into the vat he was working on at the sewage facility. News 12 Long Island spoke to residents who live in the apartment complex in Smithtown and say the workers come twice a week and always early in the morning. Dennison?s body was found just before 7 p.m. last night, so officials say he could have been at the bottom of the vat the entire day.