CANDICE AND KRISTIN: Police will not yet confirm which of the Hermeler twins died and which survived.

As grisly details emerged about what confronted Colorado police at the scene of a failed suicide pact between 29-year-old Australian twins, the survivor was refusing yesterday to tell police why they made the agreement.

Police confirmed that the twins, Candice and Kristin Hermeler, had intentionally shot themselves in the head with .22 calibre pistols at the Family Shooting Centre in Cherry Creek State Park in Denver on Monday.

Neighbours and teachers described the former students of Methodist Ladies College in Melbourne as cheerful and extremely close.

Court documents yesterday showed that when police arrived at the outdoor range a staff member was performing chest compressions on one of the women, who was on her back. She was later pronounced dead at the scene.

The documents said the second woman was sitting with blood in her hair and on the back of her head.

It was then that a police officer noticed a gunshot wound in the middle of her forehead.

The woman was well enough yesterday to be interviewed by police in hospital for two hours but she would not say why she and her sister had entered into the bizarre pact.

Captain Louie Perea, a spokesman for the Arapahoe County sheriff's office, would not reveal which twin he believed survived and which had died. He said the survivor confirmed she had entered into a suicide pact with her sister but would not say why.

''We asked that on more than one occasion and she declined to answer that question,'' he told the Sydney Morning Herald. ''She was emotional. She was … agitated, frustrated, basically ran the entire gamut of emotion.''

Police are still waiting to receive copies of the women's fingerprints from US immigration officials but said the survivor had finally identified herself to police, potentially ending her parents' wait to learn which of their daughters had died.

The women were in the Denver area for more than a month and had taken gun lessons before the incident at the range.

Workers there said they had had their hair done and were wearing make-up before the shooting.

Matthew Maruff, the principal of their former school, Girton Grammar in Bendigo, said: ''They worked hard in their classes and had good prospects in their studies.

''The Hermelers were a close family … their parents were very caring and supportive of them.''

It is believed Candice attended the prestigious University of North Carolina.

Jacqueline Sole, the twins' second cousin, said the twins loved travelling and ''didn't lack for anything'' when they were growing up.

Ernest Hermeler and his wife Kelsay were believed to be travelling to the US yesterday.

Candice and Kristin Hermeler are believed to have entered the US on cultural exchange visas but Arapahoe County police do not know who sponsored them or where they worked or trained, which is a requirement for the terms of the visas.

with AAP