Lisa Montgomery, 52, was executed by lethal injection at the Federal Correctional Complex in Terre Haute, Indiana, and pronounced dead at 1:31 a.m. Wednesday.
Montgomery was the first woman to be executed by the federal government since 1953 and was the only woman on death row.
The Supreme Court denied a last-ditch effort late Tuesday by her defense attorneys who argued that she should have been given a competency hearing to prove her severe mental illness, which would have made her ineligible for the death penalty.
She was the 11th federal death row inmate to be executed by the Trump administration after a 17-year hiatus in federal executions.
"The government stopped at nothing in its zeal to kill this damaged and delusional woman," her attorney, Kelley Henry, said in a statement. "Lisa Montgomery's execution was far from justice."
Montgomery's attorneys, family and supporters had pleaded with President Donald Trump to read their clemency petition and make an executive decision to commute her sentence to life without the possibility of parole.
Montgomery was sentenced to death in 2008 by a Missouri jury for the 2004 murder of a pregnant woman, cutting the fetus out and kidnapping it. The baby survived.
A federal judge granted Montgomery a stay of execution Tuesday for a competency hearing -- just hours before she was scheduled to be executed.
"The Court was right to put a stop to Lisa Montgomery's execution," Henry said in a statement. "As the court found, Mrs. Montgomery 'made a strong showing' of her current incompetence to be executed. Mrs. Montgomery has brain damage and severe mental illness that was exacerbated by the lifetime of sexual torture she suffered at the hands of caretakers."
"The Eighth Amendment prohibits the execution of people like Mrs. Montgomery who, due to their severe mental illness or brain damage, do not understand the basis for their executions. Mrs. Montgomery is mentally deteriorating, and we are seeking an opportunity to prove her incompetence," Henry added.
But the Supreme Court denied the effort and pleas to President Trump were unsuccessful.
Two more executions are scheduled this week, for Corey Johnson on Thursday and Dustin Higgs on Friday. Both of their executions have been halted by a federal court judge as the men are still recovering from Covid-19. Prosecutors intend to appeal the ruling on Higgs and Johnson, according to court documents.