A federal appeals court in Washington, D.C. has lifted a stay of execution for a female death row prisoner scheduled to be executed later this month.

Lisa Montgomery, the only female on the federal death row, had been scheduled to die by lethal injection in December, but a federal judge ordered a delay.

Lisa Montgomery, 52, is the only woman lingering on federal death row was set to executed by lethal injection on January 12. But on Christmas Eve, a federal court put on a halt on the forthcoming date, claiming that it violated federal regulations constituting procedures for carrying out capital punishment. (legal team (handout))

She is now set to be executed Jan. 12, but further court appeals are expected to be filed by Saturday.

Montgomery killed a pregnant Missouri woman in 2003, taking the baby girl from the womb and later tried to claim the child as her own.

After the ruling, Montgomery's attorney Meaghan VerGow said in a statement that her client should not be executed.

"Given everything we know about Lisa Montgomery’s mental illness, her lifetime of horrific torture and trauma, and the many people in positions of authority who could have intervened to save her but never did, there can be no principled reason to carry out her execution, " she said in a statement.

Kelley Henry, one of the convicted killer’s attorneys, told Fox News previously that she contracted the coronavirus in November when visiting Montgomery, delaying the preparation of her clemency case.

Henry, a Nashville public defender, said, "She is on suicide watch and has been issued the highest mental health designation."

Fox News reporter Hollie McKay contributed to this report.