Pardo, 56, a Boy Scout leader and decorated Navy veteran, was convicted of killing people he believed to be drug dealers and other criminals. At his 1988 trial, he said he was ridding the streets of the "scum of the Earth."
Lawyers for Pardo said he was insane at the time and argued he was incapable of standing trial. They argued in Miami-Dade Circuit Court he also was not granted full access to records surrounding his trial. Judge Stanford Blake denied that appeal and the state's top court upheld his decision, The Miami Herald reported Tuesday.
The courts also dismissed an appeal claiming the state's lethal injection protocol amounts to cruel and unusual punishment, saying the claim is "pure speculation and conjecture."
Gov. Rick Scott has signed a death warrant for the serial killer, who, barring any last-minute legal maneuvers, is scheduled to be executed next week.