Death row murderer Kevin Johnson gave "no statement" and declined a final meal before his execution for killing a police officer.
The 37-year-old was given the lethal injection on Tuesday evening at the state prison in Bonne Terre, Missouri after he was denied a last minute appeal by the US Supreme Court.
His 19-year-old daughter was also refused permission to watch the execution as in Missouri witnesses need to be aged 21.
Johnson was handed the death penalty for the 2005 murder of officer William McEntee from Kirkwood Police Department, who he targeted in a revenge killing after alleging he did not do enough to save his 12-year-old brother's life.
Johnson's legal team did not challenge his guilt, but claim racism played a role in the decision to seek the death penalty and in the jury’s decision to sentence him.
In addition to refusing to provide a statement, a non-mandatory element of the procedure before execution, Johnson also refused the offer of a final meal.
In a first for modern executions in Missouri, Johnson was not alone in the execution room, and was joined spiritual advisor Reverend Darryl Gray at his side.
The two men are reported to have spoken until the drug was administered.
The Reverend read from the Bible as Johnson shut his eyes, with his body movement ceasing shortly afterwards. After he was executed, he then continued reading from the Bible and praying while patting Johnson's shoulder.
Recalling the scene in the execution room, he said: "We read scripture and had a word of prayer.
"He apologised again. He apologized to the victim's family. He apologised to his family. He said he was looking forward to seeing his baby brother. And he said he was ready."
Johnson's 19-year-old daughter Khorry Ramey had pleaded with authorities to witness the execution - but state law prohibits anyone under 21 from observing the process.
His sentencing had prompted protests in the days and hours leading up to his execution, with many supporting the lawyer's assertions of racism and opposing the use of the death penalty.
A group of around 30 people could be seen protesting outside the Governor’s Mansion in Jefferson City, Missouri on Tuesday.
Some of those in attendance held up a large sign that read “Stop State Murder” while Capitol police guarded the gateway to the mansion.
A similar sized group was also seen in St Louis, where a demonstration is staged outside the Civil Courts Building.
