(CNN) -- The death of an 11-year-old boy at a Boone, North Carolina, hotel could have been prevented had police been told that the carbon monoxide that killed him was also to blame for two earlier deaths in the same room, the city's police chief said.
Chief Dana Crawford's statement Monday came three days after Watauga County Medical Examiner Brent Hall resigned.
It wasn't clear if Hall's resignation on Friday was related to the three deaths in Room 225 of the Best Western Plus Blue Ridge Plaza. Daryl Dean Jenkins and his wife, Shirley Mae Jenkins, died on April 16; 11-year-old Jeffrey Williams died on June 8.
Hall received an e-mailed copy of the toxicology report on Shirley Mae Jenkins' death from the North Carolina Department of Health and Human Services on June 1, a spokesman for the state agency said.
The report showed an often lethal concentration of carbon monoxide in her blood but did not provide a formal cause of death.
The medical examiner did not share the results with police until June 8 -- the same day Williams died, Crawford told CNN in an e-mailed statement.
Had police been told of the results sooner, Crawford said, "I would like to think that we would have contacted our county health department, The Town of Boone Fire Department and the Town of Boone Planning and Inspections Department, at a minimum and tried to find the source of the carbon monoxide entering room 225."
Repeated telephone calls by CNN to Hall on Monday and Tuesday went unanswered.
Police had requested the toxicology reports "weeks before," CNN affiliate WSOC-TV reported Friday.
According to the Charlotte station, fire investigators traced the carbon monoxide to a pool heater.
Ventilation pipes for the pool heater were installed near the heating and air conditioning units for the room where the three people died, Boone police Capt. Andy Le Beau told CNN on Tuesday. Investigators also found holes in the ventilation pipes just below the room, he said.
"The heater itself runs off of natural gas. A byproduct of the pool heater is carbon monoxide. The ventilation system that ventilates the carbon monoxide goes to outside the building, in close proximity to the heating and air conditioning units of 225," Le Beau added. "In addition, there were deficiencies found in the ventilation pipes that were in the ceiling area just below room 225. Carbon monoxide could also get into the room from that method as well."
Search warrant documents show police removed two sections of exhaust pipe for the heater from below the room, WSOC said.
CNN's Joe Sutton and Melissa Gray contributed to this report.