Kimberlee Singler, 36, has been charged in Colorado with seven counts including the first-degree murder of her nine-year-old daughter and seven-year-old son in December 2023.

Prosecutors allege Singler killed two of her children by shooting them in the head and stabbing them in the neck in their home, amid a protracted custody battle with her ex-partner.

Singler is alleged to have also tried to kill her third child, a girl then aged 11. She denies the allegations.

Judge John Zani ruled on Friday that Singler’s challenge to her extradition, on the grounds that if convicted she faces a mandatory sentence of life without parole in breach of her human rights, should be dismissed.

Lawyers representing US prosecutors said at a hearing in September that Singler “initially blamed an unknown male and cast suspicions on her former partner” for the crimes, but that this could be proved to be false.

Singler’s lawyer Edward Fitzgerald told the court at that hearing that Singler was “concerned that the statement made against her by her surviving child was not voluntary”.

Singler appeared in the dock for Friday’s brief hearing, when Zani told her he had rejected her case.

“The case now passes to the secretary of state for a decision as to whether or not extradition is to be ordered,” Zani said.

“Should the secretary of state make that decision, you have the right to ask the high court for permission to appeal against my decision.”

Singler’s lawyers declined to comment.