The doctor was bound and pummelled with a baseball bat to the point of death, but managed to crawl out of the house's basement just as it went up in flames.

His wife remained inside, already strangled to death. His two daughters, Michaela (11) and Hayley (17) tied by ropes to their beds, died in the inferno.

It all began last Sunday evening when Jennifer HawkePetit finished picking up groceries with one of her girls. As they drove home they were followed in another vehicle by the suspects, Joshua Komisarjevsky and Steven Hayes. The men did not stop at the house but went instead to a nearby Wal-Mart to buy instruments of the torture that was to come later . . . rope and an air rifle.

Just how fast the men worked, and the exact scope of the horrors they inflicted after breaking into the house at about 3am, is still not fully known. Petit was left for dead after his beating, and probably was unconscious for what followed, waking only to escape the flames. Sources said at least one daughter and her mother were raped.

Investigators say that some time in the early morning Hayes, 44, briefly left the Petit house to collect cans of petrol, presumably as fuel for the fire they already planned to start.

As for the initial motive, it may have been about money. Both men had long rap sheets for burglaries committed in the area.

Hayes had been committed to prison numerous times. Komisarjevsky had also been jailed this year for robberies. Both men were granted parole. At about 9am on Monday, one of the pair drove Hawke-Petit back to the shop where she had been the night before and forced her to withdraw $15,000 from her bank.

Bank clerks alerted the police.

Prosecutors added capital offences to the list of charges against the two men, meaning they could face the death penalty. Debate has begun over how the state's parole board came to release the two men when each had barely finished half of their sentences.