Missouri state executed late on Tuesday a transgender woman found guilty of murdering an ex-girlfriend long before she transitioned, in what is believed to be the first execution of an openly-transgender person in the US.

The 49-year-old Amber McLaughlin died by lethal injection at the Diagnostic and Correctional Center in the town of Bonne Terre. She is the first person to die by capital punishment in the US this year.

What was McLaughlin's crime?

McLaughlin was convicted in 2006 of killing ex-girlfriend Beverly Guenther three years prior. Guenther had sought a restraining order due to McLaughlin's stalking after their relationship ended.

Her body was dumped near the Mississippi river, raped and stabbed to death with a kitchen knife.

Though the jury found McLaughlin guilty of murder, they remained deadlocked regarding her punishment. A judge then utilized Missouri's unique law, which is also available in Indiana, allowing judges to issue death sentences.

The sentence was not carried out for years, though, as McLaughlin's lawyers asked for it to be commuted to life in prison, based on the fact that it was not a jury who sentenced the defendant.

How did she come to be executed?

In 2016, a court ordered a new sentencing hearing for McLaughlin. A federal court of appeals reinstated the death penalty against her in 2021.

Republican Governor Mike Parson turned down a clemency request.

"McLaughlin terrorized Ms. Guenther in the final years of her life, but we hope her family and loved ones may finally have some peace,'' Parson said in a written statement after the execution.

The request cited the abuse Mclaughlin purportedly suffered at the hands of her foster caregivers as a child and its impact on her mental health.

It said she suffered from depression and gender dysphoria, the unease one suffers when their assigned gender at birth clashes with their sexual identity. She had allegedly attempted suicide as a child and an adult.

McLaughlin began her sexual transitioning three years ago, while in prison. However, she did not receive hormone treatment and remained in the men's section of death row in Missouri.

A database on the website of the anti-execution Death Penalty Information Center, last updated in December, shows no prior record of any transgender executions since the death penalty was reinstated in the mid-1970s. It also shows that only 17 of those executed since then were women, out of 1,558.