Campaigners are fighting to halt the execution of a man who killed his girlfriend and her three children.

The president of the national NAACP civil rights group is urging Missouri governor Mike Parson to halt the execution of Raheem Taylor, who is scheduled to die by lethal injection on Tuesday.

“There are many reasons to spare Mr Taylor’s life, but they all come down to one: the State of Missouri has the life of a man in its hands, and, in this life and death decision, lies the weight of moral responsibility,” NAACP president Derrick Johnson wrote to the Republican governor.

“The evidence presented at trial does not support Mr Taylor’s conviction.”

Separately, nearly three dozen civil rights and religious groups asked St Louis County prosecuting lawyer Wesley Bell to reconsider his decision not to ask a judge for a new hearing on Taylor’s claim that he was not even in Missouri when the killings occurred.

The letter said Mr Bell has a “clear opportunity here to free an innocent black man whose case was riddled with prosecutorial misconduct, police coercion and brutality, and ineffective assistance of counsel”.

Mr Bell said in his decision that the “facts are not there to support a credible case of innocence”.

Meanwhile, former St Louis County prosecuting lawyer Bob McCulloch, whose office prosecuted the 2004 case, said Taylor’s claims of innocence are “nonsense”, and the evidence against him was overwhelming.

Taylor himself called into a church service on Sunday at Greater Fairfax Missionary Baptist Church in St Louis.

He thanked those who support him.

“Please continue to let God use you, to work through you, as a vessel because time is one of my most valuable commodities and we only have a small amount of that time, and none of it can be replaced,” Taylor told the congregation as the Rev Darryl Gray held a mobile phone to the microphone.

Taylor, 58, who previously went by the first name Leonard, shared a house in the St Louis suburb of Jennings with Angela Rowe and her children, 10-year-old daughter Alexus Conley, six-year-old daughter AcQreya Conley, and five-year-old son Tyrese Conley.

On December 3 2004, police were sent to the home after worried relatives said they had not heard from Ms Rowe.

Officers found the bodies of Ms Rowe and her children.

All four had been shot.

The execution would be the third in Missouri in three months, following those of Kevin Johnson and Amber McLaughlin.