Tests have revealed the amount of Carbon Monoxide recorded in a home where three people died was 20 times the fatal dose.
The bodies of John Cook, his wife Audrey and their daughter Maureen were found in a static home at the Tremarle Park in Camborne on Saturday.
Today Cornwall Fire and Rescue Service said they would have been 'unconscious within minutes'.
All homes at the park use gas for heating and cooking. Inspectors are examining the family's cooker.
More top news
A combination of cloud, sunshine and showers. Temperatures rising to 19 C but heavy showers - some of them thundery - are likely later.
As the country prepares to mark the centenary of the Battle of Jutland, we speak to the grandson of one of the veterans of the conflict
Friday will start with a mix of cloud, sunny spells and showers but those showers will become heavy later with temperatures hitting 19 C