The investigation continues in a workplace incident that killed a Paducah man and critically injured a Murray man in Calvert City.
Eric Young, 37, of Paducah, a maintenance employee at Quality Carriers, 76 W.C. Ave., was cleaning out a tanker-trailer at the facility Friday.
Richard Wheeler of Murray may have entered the tank to assist Young, Calvert City Police Chief David Elliot said.
Calvert City Police received an emergency call from company officials about 12:30 p.m., according to Elliot.
When police arrived, Young was dead and Wheeler was in critical condition. Both men were trapped inside the tank and had to be freed by officials with the Calvert Industrial Mutual Aid Program who are trained in confined space rescue.
Along with Calvert police, the Marshall County Sheriff's Department and Gilbertsville and Calvert City firefighters were on the scene until about 2:30 p.m.
Elliot said the investigation has been turned over to Marshall County Coroner Mitchell Lee.
An internal investigation will also be conducted by an organization that oversees plant safety procedures.
Lee said Young, who was pronounced dead at 1:42 p.m., died from asphyxiation caused by a lack of oxygen from an influx of nitrogen. The tanker was empty at the time, and had been cleaned using nitrogen.
Both Elliot and Lee said such incidents are fairly unlikely and locally there hasn't been a similar one for several years. Lee said he will continue the investigation into the circumstances around the death.
There is no timetable for releasing additional information or concluding the investigation, which depends on Wheeler's speed of recovery, according to Lee.
Wheeler was taken Friday to a hospital in Evansville, Ind. Officials at Deaconess Hospital in Evansville said he was not listed as a patient. Officials at St. Mary's Medical Center in Evansville said they couldn't disclose any information about Wheeler, including if he was a patient on Monday night.
Contact Kathleen Fox, a Paducah Sun staff writer, at 270-575-8651 or follow @kathleendfox on Twitter.