More than a week after convicting a gunman in the deadliest antisemitic attack in U.S. history, jurors began hearing arguments in federal court Monday about whether he should receive the death penalty for killing 11 worshippers inside a Pittsburgh synagogue.

The sentencing phase is expected to take four or more weeks — longer than the three weeks it took the jury to hear trial testimony and reach a verdict.

The magnitude of Robert Bowers’ crimes is staggering, prosecutor Troy Rivetti told the jury as opening statements got underway.

“He came to kill,” Rivetti said. “The defendant entered the Tree of Life synagogue, a sacred place to gather and pray, and he murdered 11 innocent worshippers.”

From the beginning, the punishment that Bowers will receive — a death sentence or life in prison without parole — has been the only question in the case, as his own attorneys admit he carried out the 2018 attack and offered only a token defense at trial.

Attorneys for Bowers have long signaled their focus would be on trying to save his life. They are expected to contend Bowers has schizophrenia, epilepsy and brain impairments.

The jury convicted Bowers on June 16, after five hours of deliberations, on all 63 counts he faced. He showed little reaction when the verdict was read.

The sentencing portion of his trial comes as the death penalty has become a more prominent topic in the 2024 presidential race. The federal death penalty wasn’t a high-profile issue until former President Donald Trump’s administration resumed executions in 2020 after a 17-year hiatus. With 13 inmates put to death in his last months in office, Trump oversaw more federal executions than any president in more than 120 years.

President Joe Biden said during his 2020 campaign that he would work to end capital punishment at the federal level and in states that still use it, and Attorney General Merrick Garland has paused executions to review policies and procedures. But federal prosecutors continue to work to uphold already-issued death sentences and, in some cases, to pursue the death penalty at trial for crimes that are eligible, as in Bowers’ case.

Prosecutors are seeking the death penalty for Bowers on two sets of capital charges — 11 counts each of obstruction of the free exercise of religion, resulting in death, and use of a firearm, resulting in death.

Bowers, 50, a truck driver from suburban Baldwin, killed 11 members of three congregations — Dor Hadash, New Light and Tree of Life — who had gathered for Sabbath activities on the morning of Oct. 27, 2018, at the Tree of Life synagogue in Squirrel Hill, the heart of Jewish Pittsburgh. He also wounded two other worshippers and five police officers, several of them severely.

Bowers spewed hateful comments toward Jews online and at the scene, fixating on a Jewish refugee-aid organization that he accused of bringing in “invaders.”

Bowers’ attorneys had offered a guilty plea in return for a life sentence without possibility of parole, but prosecutors rejected that offer. Most but not all victims’ relatives support seeking the death penalty.

The guilty verdict followed three weeks of wrenching testimony from survivors and often graphic evidence, including 911 calls from victims and photographs of the carnage. Bowers’ defense attorney, Judy Clarke, called no witnesses and offered only a brief defense. She suggested Bowers was driven not by religious hatred but by a deluded belief that by killing Jews, he was saving children from the genocide he believed was being perpetrated by immigrants aided by Jews.

The sentencing proceedings will occur in two phases.

In the first “eligibility” phase, prosecutors have to persuade the jury to decide unanimously the crime qualifies for the death penalty. If the jury agrees, it will then decide his sentence.

To deem Bowers eligible for the death penalty, the jury will have to conclude Bowers acted with intent and that there was at least one aggravating factor that raises the severity of the crime.

Prosecutors have already introduced evidence of intent — including Bowers having arrived, heavily armed, at the synagogue on a Sabbath morning, and having begun his assault just after posting on social media that he was “going in.”

Prosecutors have signaled they plan to show several aggravating factors — that Bowers undertook substantial preparation and premeditation, preyed on vulnerable persons (several victims were over 70, and two were developmentally disabled), killed multiple people and put others at grave risk of death.

Each side is expected to call about eight witnesses in the weeklong eligibility phase.

University of Pittsburgh law professor David Harris predicted the jury will likely find him eligible for the death penalty, given the overwhelming evidence involved.

The main battle, expected to take at least three more weeks, will be over the sentence. The jury will hear victim impact statements — demonstrating the trauma suffered by survivors and the victims’ loved ones — as well as mitigating factors that might prompt a more lenient sentence, which may include pleas from his relatives.

Bowers’ lawyers indicated during jury selection they plan to raise issues about Bowers’ mental state and his childhood difficulties.

To put him on death row, jurors will have to agree unanimously the aggravating factors outweigh the mitigating ones.

Clarke has also represented other killers in high-profile capital cases. They include Boston Marathon bomber Dzhokhar Tsarnaev, who is currently appealing his death sentence, as well as 1996 Olympics bomber Eric Rudolph and the late Unabomber Ted Kaczynski, who both received life sentences.

“Mitigating evidence – that’s her specialty,” Harris said of Clarke. “You’ll hear anything that’s possible” to spare Bowers’ life.

Local Jewish leaders expect to hear a sympathetic portrait of the killer, about whom relatively little has been known publicly until now, and are worried it will be traumatic. “So we’re going to be learning what kind of horrible human being he really is,” New Light Congregation co-president Stephen Cohen said after the verdict was issued.

(AP)