Nathaniel Woods' execution cast scrutiny on Alabama's death penalty. So why is the cop killer who pulled the trigger still alive?

While the family of Nathaniel Woods fumes over his execution and prepares for his funeral, the man who confessed to acting alone in the killing of three Alabama police officers that landed them both on death row is alive and may never be executed, according to his former appellate attorney.

As a wave of outrage swept the state and nation over Woods' execution late Thursday, Alabama's death penalty laws are being scrutinized by civil rights leaders and labeled as unjust by Woods' supporters, saying its criminal courts are unfair to minority defendants.

But the former attorney for Kerry Spencer, the man convicted of gunning down three police officers in a Birmingham crack house in 2004, said he hopes the execution will put a final nail in the death penalty in Alabama and the 28 other states where it still exists.

"If that can't be a poster case for eliminating the death penalty, I don't know what will," retired defense attorney Charles Flowers III told ABC News on Friday. "The only thing good that can come out of this whole mess is if this particular case is the stimulus to showing people how terrible the death penalty is, because you can't administer it fairly."

Woods was killed by lethal injection on Thursday night at the William C. Holman Correctional Facility in Atmore, Alabama, despite his family and supporters, including Martin Luther King III, son of the civil rights icon, and Kim Kardashian West, contending there was overwhelming evidence that he was likely innocent.

King called the decisions of Alabama Gov. Kay Ivey not to intervene and the U.S. Supreme Court not to halt Woods' death "reprehensible" and a "mockery of justice and constitutional guarantees to a fair trial."

Flowers said that despite Spencer claiming he acted alone in the 2004 Birmingham triple murder, he might end up never being put to death.

That's because when Spencer was convicted in 2005, the jury that found him guilty reached a non-unanimous verdict in the death penalty phase of his trail and recommended he be sentenced to life in prison without parole. The judge in the case, however, overrode the jury's decision and sentenced Spencer to death.

Then, in 2017, the Alabama state legislature passed a law that stripped judges of their discretion to override non-unanimous jury verdicts in death penalty cases, effectively declaring such decisions in violation of the Sixth Amendment guaranteeing the rights of criminal defendants to a jury finding.

As one of her first acts as Alabama's governor, Ivey, whose decision condemned Woods to death, signed the bill.

While the law stopped short of making it apply retroactively to inmates like Spencer, Flowers and other death penalty experts say it is only a matter a time until it becomes retroactive as more convicts on death row prior to the passage of the law challenge it and eventually force the U.S. Supreme Court to rule on the issue.

Meanwhile, the jury that heard Woods' trial, which preceded Spencer's conviction, also reached a non-unanimous verdict of 10-2 and recommended a sentence of death, which was accepted by the trial judge.

"If what I think is going to happen happens, if the Supreme Court bars Kerry's execution, which I certainly hope they do, and Woods was executed, you're going to have a situation where a man who probably didn't have a thing in the world to do with something was executed, and the man who pulled the trigger is not," Flowers said.

Robert Dunham, executive director of the Death Penalty Information Center, a nonprofit organization in Washington, D.C., that focuses on disseminating studies and reports related to capital punishment, said Flower could very well be right.

"It's inherently arbitrary to say that some practice is so unreliable that it's unconstitutional and then to allow death sentences that were imposed based on that unreliable practice to stand," Dunham told ABC News. "So that is the issue, but so far there hasn't been a declaration that it's unconstitutional because almost everybody else has repealed it and the Supreme Court hasn't yet addressed it."

According to the Equal Justice Initiative, a Montgomery, Alabama, nonprofit that provides legal representation to prisoners who may have been wrongly convicted of crimes, Alabama judges have overridden jury recommendations 112 times since the death penalty was reinstated in 1976, including 101 times in which they issued death sentences.

Dunham said another issue Woods' execution has cast into the national spotlight is that of non-unanimous juries.

The U.S. Supreme Court is expected to soon make a decision on the constitutionality of non-unanimous verdicts.

In a decision that only applied to federal cases, the Supreme Court in 1972 struck down the practice as a vestige of the Jim Crow era meant to discriminate against African Americans. The court said the Sixth Amendment's guarantee of a fair trial means jury verdicts in felony trials must be unanimous.

Alabama and Oregon are the last states in the nation that allow non-unanimous jury verdicts in felony cases. The case before the Supreme Court pertains to Louisiana.

While Louisianans voted in November 2018 to repeal non-unanimous jury verdicts, Louisiana convict Evangelisto Ramos, who maintains his innocence in a gruesome murder case, wants the high court to force the state to apply their new rules retroactively and give him a new trial. Ramos was convicted by 10 of 12 jurors in his second-degree murder trial and sentenced to life without parole.

While hearing oral arguments in the case in October 2019, Justice Brett Kavanaugh, the newest member of the Supreme Court, noted that "the rule in question here is rooted in racism ... rooted in a desire, apparently, to diminish the voices of black voters."

Florida and Delaware were among the most recent states to repeal the practice, in addition to Louisiana.

Dunham, who has studied both Woods' and Spencer's cases, said that while it was the same crime, the legal representation that each man received and the evidence presented at their separate trials was vastly different.

"Woods got terrible representation and there are all sorts of issues that were never raised and all sorts of evidence that was never presented that was presented in Spencer's case," Dunham said.

During his trial, Spencer testified that he acted alone when he fatally shot Birmingham police officers Carlos Owen, Harley Chisholm III and Charles Bennett, and wounded a fourth officer. He claimed he fired in self-defense when the officers pulled guns on him and swore the shooting was not premeditated or planned as prosecutors alleged.

Woods' jury never heard Spencer's self-defense claim, Dunham said.

"If Woods' jury had heard that, there's a very strong possibility that they would have acquitted because it destroys the prosecution's theory that essentially he led them into an ambush," Dunham said. "I mean, Spencer says, 'Woods couldn't possibly have known I was going to shoot the officers [because] I didn't know I was going to shoot the officers.'"

He said that during Woods' trial, his girlfriend testified that he hated police officers, a contention that dovetailed into the prosecution's theory that Woods lured them into a death trap. The girlfriend, however, later recanted her testimony and claimed she was coerced by police, Dunham said.

The officer who survived the shooting testified at Woods' trial that Woods cursed at officers when they initially arrived at his home and challenged one to take off his badge and fight him, according to trial transcripts included in Woods' appeal.

"He [the officer] testified in Spencer's case, too, and never mentioned anything of the sort," Dunham said.

Woods also claimed his lawyer convinced him to reject a plea deal prosecutors offered him of 20 to 25 years in prison, according to court records.

"The reason that this case attracted so much attention is because it's an outrageous case. And Alabama's response to that wasn't to concede that there were problems, it was to push ahead and pretty much double down on all of the assertions that seemed questionable to start with," Dunham said.

"When we think of important moments in civil rights that changed public opinion, like Bull Connors siccing the dogs and putting the hoses on the peaceful marchers, it was such an inappropriate response and everybody saw it right out in the open," he said. "Here, Alabama had an inappropriate response and everybody saw it right out in the open. The subject matter is not the same, but what you have is something that looks like injustice and it looks like Alabama doesn't care."

But Ivey said in a lengthy statement released following Woods' execution that she declined to intervene and grant a reprieve "after a thorough and careful consideration of the facts surrounding the case."

"A jury of Mr. Woods’ peers convicted him of four counts of capital murder. In the past 15 years, his conviction has been reviewed at least nine times, and no court has found any reason to overturn the jury’s decision," Ivey said in her statement. “Under Alabama law, someone who helps kill a police officer is just as guilty as the person who directly commits the crime."