Amber McLaughlin is thought to be the first transgender woman to have been put to death after her fate was sealed when a clemency request was denied.
The 49-year-old was on death row in a prison in Missouri for killing a former girlfriend in 2003 in St Louis - a crime she was convicted for in 2006.
Republican governor of Missouri, Mike Parson, on Tuesday declined McLaughlin a clemency request based on her traumatic childhood and serious mental health issues - both of which the jury never heard about during the trial. McLaughlin’s legal team noted that the jury deadlocked on the decision, leaving the judge to make a unilateral call.
The death penalty is legal in many US states but in 2022 was only practised in Alabama, Arizona, Mississippi, Missouri, Oklahoma and Texas. However, only Missouri and Indiana allow a judge, rather than a jury, to sentence someone to death.
Two Missouri members of Congress, Democrats Cori Bush and Emanuel Cleaver, wrote to Mr Parson - calling executions a “moral depravity”.
Their letter said: “They are not about justice; they are about who has institutional power and who doesn’t. We urge you to correct these injustices using every tool available, including the power to grant clemency.”
McLaughlin underwent gender transition while incarcerated and is thought to have been the first transgender person to have been executed. Her crimes were committed long before she transitioned.
In 2003, she was in a relationship with Beverly Guenther but after they broke up McLaughlin would show up at the suburban St Louis office where the 45-year-old worked. Ms Guenther obtained a restraining order, and police officers occasionally escorted her to her car after work.
Ms Guenther's neighbours called the police the night of November 20, 2003, when she failed to return home.
Officers went to the office building, where they found a broken knife handle near her car and a trail of blood.
A day later, McLaughlin led police to a location near the Mississippi River in St Louis, where the body had been dumped.
Authorities said she had been raped and stabbed repeatedly with a steak knife.
A court in 2016 ordered a new sentencing hearing, but a federal appeals court panel reinstated the death penalty in 2021.
"McLaughlin terrorised Ms Guenther in the final years of her life, but we hope her family and loved ones may finally have some peace," Mr Parson said in a written statement after the execution.
McLaughlin began transitioning about three years ago, according to Jessica Hicklin, who spent 26 years in prison for a drug-related killing before being released a year ago. Ms Hicklin, now 43, sued the Missouri Department of Corrections, challenging a policy that prohibited hormone therapy for inmates who were not receiving it before being incarcerated.
Ms Hicklin won the lawsuit in 2018 and became a mentor to other transgender inmates, including McLaughlin. McLaughlin did not receive hormone treatments, however, Mr Komp said. The Bureau of Justice Statistics has estimated there are 3,200 transgender inmates in the nation's prisons and jails.
“I am sorry for what I did,” McLaughlin said in a final, written, statement. "I am a loving and caring person."
A database on the website for the anti-execution Death Penalty Information Centre shows that 1,558 people have been executed since the death penalty was reinstated in the mid-1970s. All but 17 of those put to death were men.
