The territory's coroner has confirmed that carbon monoxide killed three of the five people who died in a Porter Creek home in late January.

Sharon Hanley said today test results have come back for Valerie Rusk and her two children, 13-year-old Gabriel and 11-year-old Rebekah.

All three had high levels of carboxy hemoglobin.

Carboxy hemoglobin is a mix of carbon monoxide and hemoglobin in the blood stream. High levels prevent oxygen from being carried through the body.

Hanley said anything exceeding 40 per cent is considered severe poisoning, while anything around 60 per cent is likely to be fatal.

Valerie Rusk had levels in the 80s. Her children's levels were in the 90s.

Toxicology results for the two others who died in the house – Bradley Rusk and family friend Donald McNamee — have not been released by the Vancouver lab yet.

Hanley said she doesn't expect those results to be any different from the other three.

The tests provide no way of telling exactly how long the family and McNamee were dead before being found by a concerned family friend.

All had been complaining of feeling unwell and taken time off of work and school leading up to their bodies being found in the Centennial Street house.

Hanley said she has not decided if an inquest will be held into the deaths.

The territory's fire marshal has not completed his report into the tragedy.

Officials have said they are focusing on the oil-fired boiler system used to heat the home.

In the days following the deaths, carbon monoxide detectors flew off Whitehorse shelves.

Multiple reports going back to 2007 warned the government about dangerous oil-fired appliances in the territory.

The most recent one, published in 2010, show most oil furnaces in Whitehorse and Haines Junction — where the surveys were completed — are not up to national code standards.

The official Opposition has called on the government to implement mandatory training and licensing program for oil burner mechanics, and require landlords to install and maintain carbon monoxide detectors.