A US mother charged with murdering two of her young children has lost her fight to avoid extradition from the UK.

Kimberlee Singler’s nine-year-old daughter Elianna Wentz and seven-year-old son Aden Wentz were found dead in a property in Colorado after being shot in the head and stabbed in the neck on 19 December 2023, police said.

Singler’s 11-year-old daughter was also at the scene with an injury after she was slashed with a knife, officers added.

Prosecutors allege the 36-year-old carried out the attacks in Colorado Springs amid a protracted custody battle with her ex-partner.

Singler had superficial knife wounds at the scene of the murders and was initially treated as a victim.

However that changed when her surviving daughter, who initially said she had been attacked by an intruder, told police her mother tried to kill her.

Despite initially co-operating with the investigation, Singler reportedly disappeared on 23 December 2023 and a warrant was issued for her arrest on murder charges.

She was arrested by the National Crime Agency in Kensington, west London, on 30 December 2023 and appeared at Westminster Magistrates’ Court on New Year’s Day facing extradition to the United States.

She has been charged with two counts of first-degree murder, one count of attempted murder, three counts of child abuse and one count of assault.

Singler has denied that she harmed her children and told police that her ex-husband had either carried out the killings or hired a hitman.

Following her arrest in London, Singler’s lawyer argued that sending her back to the US would violate European human rights law, in part, because she faces a sentence of life in prison without parole in Colorado if convicted of first-degree murder.

Such a sentence would be inhumane because it offers no prospect for release even if she is rehabilitated, lawyer Edward Fitzgerald added.

Prosecutor Joel Smith said the judge only had to consider if there is a mechanism that could allow Singler to be freed someday.

“Prospect of release – that is not your concern,” Mr Smith told the judge at a hearing in December.

District Judge John Zani rejected Singler’s challenge at Westminster Magistrates’ Court today.

Singler, wearing a teal jumper and jogging bottoms, was remanded into custody

Home Secretary Yvette Cooper will now decide whether she is to be extradited to the US.

The 11-year-old daughter has said Singler gave the children milk with a powdery substance to drink and told them to close their eyes as she guided them into a sibling’s bedroom on the day of the attack, prosecutors said.

“The defendant told her that God was telling her to do it, and that the children’s father would take them away,” Mr Smith said at a previous hearing.