The US Supreme Court Tuesday denied an application to stay the execution of Kevin Johnson, a man convicted of murdering a police officer. Johnson had filed a petition to stay his execution with the court alleging racial bias throughout his prosecution.

The petition to the US Supreme Court was presented to Justice Brett Kavanaugh and subsequently denied. Justices Sonia Sotomayor and Ketanji Brown Jackson dissented, however, saying they would have granted the application to stay. 

Johnson had also filed a motion to stay with the Missouri Supreme Court. Johnson’s attorneys and the St. Louis Prosecutor’s Office both submitted motions to stay Johnson’s execution to the Missouri Supreme Court, hoping to investigate his claims of racial prejudice throughout his trial. However, both motions were overruled by the court on Monday. 

Johnson was also denied clemency by Missouri Governor Mike Parson on Monday. Parson released a statement confirming Johnson’s scheduled execution, saying that “the violent murder of any citizen, let alone a Missouri law enforcement officer, should be met only with the fullest punishment state law allows.”

Johnson’s daughter, Khorry Ramey, also filed an emergency challenge to Missouri’s law preventing people under 21 from attending an execution. Her challenge was denied last week.

According to a report from NPR, commissioned by St. Louis’s River City Journalism Fund, the special prosecutor investigating Johnson’s claims found that prosecuting attorney Bob McCulloch intentionally excluded jurors of color from Johnson’s second trial. Additionally, of McCulloch’s 23 death penalty convictions, 15 were black men. An expert for Johnson’s legal team also found that cases involving a white victim were 3.5 times more likely to receive the death penalty than cases involving Black victims.

Johnson’s execution went ahead on Tuesday morning and he was executed by lethal injection.