When the sentencing trial for the gunman who killed 17 people at Marjory Stoneman Douglas High School in Parkland, Fla., in 2018 begins on Monday, a 12-person jury will decide whether Nikolas Cruz will receive the death penalty—or to life in prison without parole.
Cruz, 23, pleaded guilty in October to 17 counts of first-degree murder—so the court proceedings will not focus on whether he committed the shooting, but what his punishment should be. In order for Cruz to be executed, the jury’s decision at his sentencing trial must be unanimous.
The trial comes as the country is grappling with a spate of recent mass shootings, including one at Robb Elementary School in Uvalde, Texas, that left 21 people dead and sparked comparisons to the Parkland shooting.
“We’ve never had a trial like this,” says Robert Jarvis, a law professor at Nova Southeastern University in Fort Lauderdale, Fla. The Parkland trial represents the deadliest mass shooting to go before a jury in the U.S. “This trial is, in a sense, unprecedented,” Jarvis says.
Jarvis notes that in the 10 deadliest mass shootings in U.S. history, eight of the gunmen—including those at Virginia Tech in 2007 and Sandy Hook Elementary School in 2012—died by suicide or were killed by police.
The man accused of killing 23 people in 2019 at a Walmart store in El Paso, Texas, has pleaded not guilty and is still awaiting trial.
Overall, nearly 60% of mass shooters have died on scene, according to the Violence Project, a nonprofit research center aimed at violence prevention, which analyzed public mass shootings that took place from 1966 to 2020. About 11.5% of all mass shooters ultimately received a death sentence, the project found.
The gunman convicted of killing nine Black church members in Charleston, S.C., was sentenced to death in 2017, but has appealed the decision.
The Parkland trial gets underway
Cruz pleaded guilty to 17 counts of murder and 17 counts of attempted first-degree murder in the 2018 attack at his former high school, during which he killed 14 students and three staff members and wounded 17 others.
Defense attorneys for Cruz had requested a delay on June 3, arguing that the “wave of emotion” surrounding the Uvalde shooting would threaten Cruz’s right to a fair trial because the news “opened old wounds” for the community in Broward County, Fla., where the trial is taking place.
But Circuit Judge Elizabeth Scherer, who is presiding over the sentencing trial, declined to delay proceedings. “As tragic as these events were, the recent shooting tragedies in Buffalo and Uvalde have not compromised nor negatively impacted these proceedings,” Scherer wrote in a ruling on June 30. “There has not been any negative impact to his fair trial rights and there is no basis to continue this matter.” Ultimately, a jury of seven men and five women was selected.
As opening arguments begin, defense attorneys are expected to argue that Cruz struggled with mental health issues, and to focus on mental illness as a mitigating factor in arguing that he should not be executed.
“A lot is going to emerge around the perpetrator’s background, what the pathway to violence looked like for him, his state of mind,” says Jillian Peterson, co-founder of the Violence Project and an associate professor of criminology and criminal justice at Hamline University in Minnesota.
Meanwhile, prosecutors are likely to focus on the “hard evidence” of the shooting, says Jennifer Zedalis, director of trial practice at the University of Florida Levin College of Law. The jury will likely hear testimony from shooting survivors and statements from family members of those who were killed. Prosecutors are planning to present hundreds of pictures and videos of victims, though defense attorneys have sought to limit the number of photos that can be introduced as evidence.
“It feels like if the death penalty was designed for anyone, it’s someone who’s murdered this many people,” says Peterson, who has researched the backgrounds of mass shooters. “On the other hand, I think we know from our research that these perpetrators tend to have a very strong mitigation case, in terms of what that pathway to violence looks like and trauma, mental health, suicidality, and all those things.”
Jarvis thinks it’s unlikely that Cruz will be sentenced to death, given that a death-penalty decision needs to be unanimous. Defense attorneys only have to persuade one juror in order for Cruz to be sentenced to life in prison.
“The pressure is all on the prosecution,” Jarvis says. “The chances of all 12 jurors agreeing—that’s very, very unlikely.”
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Write to Katie Reilly at Katie.Reilly@time.com