Sen. Kamala Harris (D-Calif.) participates in a Democratic presidential debate on July 31 in Detroit. (Paul Sancya/AP)

Democratic Sen. Kamala D. Harris’s record on capital punishment may best be understood in three distinct chapters, but on the debate stage in Detroit on Wednesday, Rep. Tulsi Gabbard (D-Hawaii) managed to distill it down to one biting retort.

“The people who suffered under your reign as prosecutor, you owe them an apology,” she told Harris, the former attorney general of California.

Gabbard singled out Harris’s stance on the death penalty, accusing her of keeping “innocent people” on death row and saying she “blocked evidence” that could have helped them. The tense exchange illuminated a complicated piece of Harris’s record as a prosecutor that has drawn criticism from both sides of the aisle, with some targeting her refusal to seek the death penalty in the killing of a police officer, and others attacking her decision to defend California’s death penalty from a statewide legal challenge.

The result is a track record that doesn’t quite fit into the black-and-white boundaries of a debate. While Gabbard attacked other parts of Harris’s record as a prosecutor, including her treatment of marijuana cases and failure to change the money bail system, her claim that Harris kept an innocent man on death row drew the fiercest response.

“My entire career,” Harris said, “I have been opposed, personally opposed, to the death penalty, and that has never changed, and I dare anybody who is in a position to make that decision to face the people I have faced and to say, ‘I will not seek the death penalty.’”

One of those people was Renata Espinoza, the widow of a San Francisco police officer who was shot and killed in the line of duty. That was chapter one in Harris’s stance on lethal punishment.

Harris had only recently been sworn in as the new district attorney in San Francisco when Officer Isaac Espinoza was gunned down the night before Easter in 2004. She ran her campaign on a promise not to seek the death penalty, and before Espinoza was even buried, she followed through on it. She announced three days after the shooting that she would not seek the death penalty in Espinoza’s case. The anti-death penalty position, a popular stance among liberal voters, suddenly thrust the new district attorney into political chaos.

Renata, for one, was shocked.

“I felt like she had just taken something from us,” she told CNN earlier this year, in what she said was her first on-camera interview in 15 years. “She had just taken justice from us. From Isaac. She was only thinking of herself.”

The police union and greater law enforcement community was flummoxed, but even some Democrats joined the criticism.

As Harris sat at Espinoza’s funeral, Sen. Dianne Feinstein (D-Calif.) got up before the congregation and said, “This is not only the definition of tragedy, it’s the special circumstance called for by the death penalty law.” With that, rows of police officers erupted in a standing ovation — while some turned to Harris, as CNN reported.

Still, Harris didn’t budge.

“For those who want this defendant put to death,” she wrote in an op-ed in the San Francisco Chronicle days later, “let me say simply that there can be no exception to principle. I gave my word to the people of San Francisco that I oppose the death penalty, and I will honor that commitment despite the strong emotions evoked by this case.”

But 10 years later, anti-death-penalty advocates who praised Harris’s consistency in her conviction were confused when an opportunity to abolish capital punishment in the state arose — and Harris, who became California attorney general in 2011, seemed to be on the other side of the aisle.

Then came chapter two.

In a scathing July 2014 ruling, a federal judge in California ruled the state’s death penalty to be unconstitutional, finding that prisoners were kept on death row for so long — many for decades — that it violated the Eighth Amendment’s ban on cruel and unusual punishment. U.S. District Judge Cormac J. Carney described California’s execution system as “arbitrary” and “dysfunctional.”

Despite her personal opposition, Harris had promised to enforce capital punishment in her official capacity during her run for attorney general. And again, she followed through.

“I am appealing the court’s decision because it is not supported by the law, and it undermines important protections that our courts provide to defendants,” Harris announced in a statement the following month. “This flawed ruling requires appellate review.”

Liberals in the legal community were taken aback. Some started a petition urging her not to appeal, but in the end Harris won the case, and the death penalty continued in California until Gov. Gavin Newsom (D) took office this year and announced a moratorium.

“It was a big disappointment,” Hadar Aviram, a University of California Hastings College of Law professor who started the petition, told the Sacramento Bee in 2016 about Harris’s decision. “I was surprised to see a proclaimed and vocal opponent of the death penalty take steps to actively to defend it.”

Harris has offered clear-cut explanations over the years for this decision, including on the 2020 campaign trail, insisting she was duty-bound to fight for her client, the California Department of Corrections, and that she also feared Carney’s argument lambasting the delays in carrying out executions might actually be used in other cases to hasten them. “Justice is something you don’t speed up,” she told the San Francisco Chronicle this year.

But the one death penalty controversy Harris has not fully explained, at least until now, is the case of Kevin Cooper, a man on death row who has proclaimed his innocence for the past 35 years but who was denied essential DNA testing while Harris was the state’s attorney general. That’s the third chapter, which Gabbard reopened on Wednesday night.

“She blocked evidence that would have freed an innocent man from death row until a court forced her to do so,” Gabbard said, adding: “There is no excuse for that.”

Just as she was running for the U.S. Senate in 2016, Cooper’s attorneys filed a 235-page clemency petition insisting that newly available DNA testing would exonerate Cooper, who had been on death row since 1985. He was convicted of hacking a family to death, including their 10-year-old daughter and an 11-year-old neighbor. But curiously, an 8-year-old witness initially described the perpetrators as three white men, and brown and blond hairs were found in the victims’ hands, as the New York Times’s Nicholas Kristof reported in a 2018 investigative column. Cooper was black and had an afro.

A woman called police to say she believed her boyfriend, a convicted murderer, was involved in the slayings after finding his bloody coveralls and noticing a missing hatchet. And yet, police still pursued Cooper, whom they found in hiding near the family’s home after he’d escaped from a prison on a burglary conviction, Kristof reported. Sheriff’s deputies couldn’t find any of Cooper’s fingerprints or hair at the scene, however.

Years later, multiple federal judges would question whether the evidence the state did have on Cooper was planted. In 2009, four judges on the U.S. Court of Appeals for the 9th Circuit joined Judge William A. Fletcher in a dissent that began, “The State of California may be about to execute an innocent man.” His execution was ultimately stayed. Later, Kristof reported, Fletcher said during a lecture in 2013, “He is on death row because the San Bernardino Sheriff’s Department framed him.”

In 2016, Harris’s office refused to allow the DNA testing Cooper’s attorneys asked for; then-Gov. Jerry Brown (D) also did nothing, Kristof reported. Despite Gabbard’s claims, a court never forced Harris to do the tests. Instead, Newsom took office and allowed the DNA testing to move forward in February.

After Kristof published his column last year, Harris, then in the Senate, called him to say, “I feel awful about this.” In a statement, she said she hoped the governor and the state would grant Cooper the DNA testing.

A campaign spokesman for Harris told The Washington Post on Thursday morning that Harris was not directly involved in the decision to deny Cooper’s petition in 2016.

“Senator Harris ran an office of 5,000 people and takes responsibility for all the actions of the [California] Department of Justice during her tenure,” the statement said. “Most of the legal activity around this case occurred before her terms in office, but this specific request was made to and decided by lower level attorneys. When the case was brought to her attention, she publicly called for further DNA testing. She has always been a strong proponent of DNA testing and again, an opponent of the death penalty.”

After the debate, Harris dismissed Gabbard’s attacks. As a “top-tier candidate,” she told CNN’s Anderson Cooper, she expected to take hits from other candidates, “especially when people are at zero or 1 percent or whatever [Gabbard] might be at,” she said.