Two teenage Australian girls were sentenced to prison for life Wednesday for strangling a teen after a party as an experiment.

The pair, who cannot be identified because of their ages, were sentenced in the Perth Children's Court after pleading guilty to murdering Eliza Jane Davis in the West Australian coal mining town of Collie in last June.

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The court was previously told the three teenagers stayed overnight in the same house after a party, with Davis in one bedroom and the two other girls, then 16, together in another room.

As the two girls chatted after the party, each of them said they thought they would not feel bad about killing somebody, and decided to test the theory, the court was told.

They strangled Davis and buried her body under the house, then reported the girl missing and joined the search for her. They later surrendered, believing they would eventually be caught.

The girls told police that they knew it was wrong to kill, but that killing Davis "felt right," the court was told.

They "planned the murder with calmness, consideration, emotional detachment and the desire to have the experience of killing someone," prosecutor Simon Stone said.

Children's Court President Denis Reynolds described the murder as "gruesome and merciless in the extreme."

He sentenced them to life in prison, with a minimum of 15 years to be served before they are eligible for parole.

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