Judge Judith Acker died in court on Wednesday after a three-week trial, her lawyer said.
Acker, 51, was convicted in January of murdering her husband, judge and former US Senator Tanya Becker, in a 2010 death-row murder that left the former state senator with cerebral palsy and a chronic disease.
Judge Judith Aker, who died in custody, was accused of killing her husband and her husband’s former partner, Judge Tanya, during a botched bid to end the marriage and their relationship, prosecutors said in court papers.
The case against Judge Acker was the second time in as many months that the US justice system has faced questions about the conduct of its judges.
A court in Colorado, where Acker lives, also convicted her of murder in July.
In October, US President Donald Trump told a news conference in New York City that the death penalty for Acker had been overturned because of “tremendous pressure” from Democrats and “some people in the press”.
The president also said that Acker should have been spared the death sentence because of her age.
Judge Acker did not attend the hearing.
In September, she told reporters that she was “not very happy” with the outcome of her trial.