Michelle Byrom
Michelle Byrom due to be executed on Thursday

Mississippi is set to execute its first woman in 70 years.

Michelle Byrom, 57, has been given the death sentence for arranging the murder of her husband – despite multiple confession letters from her son Edward saying he was responsible for the killing.

She was found guilty of hiring her son's friend, Joey Gillis to kill her husband in exchange for $15,000, (almost £10,000),  in 1999.

Her son Edward was previously sentenced to 30 years in prison as part of the conspiracy but was freed on a supervised release. Gillis was also released after reaching a plea agreement.

Prosecutors argued the mother was primarily responsible for organizing the murder.

During the capital murder trial her son testified against her, claiming she was the mastermind behind the death of his father and that Gillis was responsible for the shooting.

The Mississippi state Supreme Court upheld her conviction in a 5-3 ruling, though Judge Jess Dickinson argued she deserved a retrial, criticising her poor legal counsel, which failed to produce mitigating evidence that she "suffered a lifetime of physical, sexual, and emotional abuse,"

He wrote: "I have attempted to conjure up in my imagination a more egregious case of ineffective assistance of counsel during the sentencing phase of a capital case. I cannot."

The US Supreme Court also declined to hear the case .

Former state Supreme Court Justice Oliver Diaz Jr, who was also in favour of a new trial, told prosecutors Clarion-Ledger he could not believe she was about to be killed.

"There's no way justice was done in this case," he said. "If an execution is allowed to proceed, we all are complicit in it in Mississippi."

The execution is due to take place on Thursday.