Missouri man to be executed for murder of police officer
Kevin Johnson with his daughter Corionsa 'Khorry' Ramey(AFP)

A man convicted of murder is to be put to death in the midwestern US state of Missouri on Tuesday in an execution that his 19-year-old daughter has been barred from witnessing.

Kevin Johnson, a 37-year-old African American man, was sentenced to death for the 2005 murder of a white policeman in a suburb of St Louis.

Johnson is set to be executed by lethal injection at 6:00 pm Central Time (0000 GMT) in a prison in the town of Bonne Terre.

Johnson's daughter, Corionsa "Khorry" Ramey, sued to be allowed to witness her father's execution but a federal court turned down her request because she is below the minimum state age of 21.

"I'm heartbroken that I won't be able to be with my dad in his last moments," Ramey said in a statement following the court decision.

"My dad is the most important person in my life," she said. "He has been there for me my whole life, even though he's been incarcerated.

"He is a good father, the only parent I have left," Ramey said. "He has worked very hard to rehabilitate himself in prison."

Corene Kendrick, a lawyer for Ramey and the American Civil Liberties Union, condemned the court's refusal to allow her client to attend the execution.

"Compounding her pain and grief by barring her from being with her father will do nothing to provide closure or healing to anyone else," Kendrick said.

"If 19 is not old enough to witness an execution, then the state should spare Mr Johnson's life for what he did when he was 19."

Johnson was convicted of shooting and killing a white police sergeant on July 5, 2005, two hours after the death of Johnson's 12-year-old brother from a seizure.

Police officers were at the family home at the time to serve an arrest warrant for Johnson and he blamed the police for his brother's death.

Johnson's lawyers have filed last-minute appeals in a bid to save his life, arguing that his 2007 conviction was tainted by racial discrimination.

A special prosecutor appointed to look into the case asked for a stay of execution, citing evidence of racial discrimination on the part of the state prosecutor.

But the Missouri Supreme Court rejected the request late Monday.

If the execution goes ahead, Johnson would be the 17th inmate put to death in the United States this year.

© Agence France-Presse