A federal appeals court has refused to stop this week’s execution of a Houston man for gunning down a police sergeant more than 12 years ago.

A three-judge panel of the 5th U.S. Circuit Court of Appeals ruled 2-1 late Monday against an appeal from lawyers for condemned killer Anthony Haynes. Haynes faces lethal injection Thursday evening in Huntsville.

Attorneys contend Haynes had poor legal help at his trial. They argue his lawyers didn’t show jurors there were mitigating factors that led to the shooting of Houston police Sgt. Kent Kincaid and Haynes shouldn’t be put to death.

Haynes still can appeal to the U.S. Supreme Court.

Prosecutors say Haynes opened fire at Kincaid’s car. The officer was shot when he stopped Haynes to ask about the gunfire.

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