[9] Bowers had earlier posted antisemitic comments against HIAS (formerly, Hebrew Immigrant Aid Society) on the online alt-tech social network Gab.

Referring to Central American migrant caravans and immigrants, Bowers posted a message on Gab in which he wrote that "HIAS likes to bring invaders in that kill our people.

[26] This 2018 mass shooting took place soon after Columbia University and the Anti-Defamation League independently reported a spike in antisemitic activity online, especially on the popular social networking platforms Instagram and Twitter.

[31] In August 2017, the widely publicized Unite the Right rally in Charlottesville, Virginia featured Nazi symbols, salutes, and the slogan "Blood and Soil",[31] among other racist and antisemitic rhetoric.

The cover picture was a photo with the number 1488, which is used by neo-Nazis and white supremacists to evoke David Lane's "Fourteen Words" and the Nazi slogan Heil Hitler.

In addition, he reposted comments in support of the four men behind the beating of DeAndre Harris and the Southern California-based alt-right fight club Rise Above Movement (RAM) in the August 2017 Unite the Right rally in Charlottesville, Virginia.

Bowers also posted comments in support of the "Western chauvinist" Proud Boys led by Gavin McInnes, who were arrested the same month for engaging in a fight with Antifa outside the Metropolitan Republican Club in New York City.

[86] In the weeks before the shooting, Bowers made antisemitic posts directed at the HIAS-sponsored[11][12] National Refugee Shabbat[87] of October 19–20, in which Dor Hadash[13] participated.

"[51][88][60] According to the Southern Poverty Law Center, "the mention of 'optics' references a disagreement that has raged within the white nationalist movement since the Unite the Right rally in 2017 about how best to get their message across to the general public".

[9][99] The defense offered a plea deal in which Bowers would plead guilty in exchange for a sentence of life imprisonment without parole; federal prosecutors declined, seeking the death penalty instead.

[103] In January 2022, after holding an earlier evidentiary hearing, Judge Ambrose denied Bowers's motion to suppress evidence of statements he made after being arrested by police, inside an ambulance, and at the hospital the day of the attack.

[113] Evidence presented to the jury included recordings of 9-1-1 calls as the attacks unfolded (including from some of the people killed), and testimony from police officers who ultimately subdued the gunman; from expert witnesses on medicine, guns, and computers; from the FBI agents and police detectives who investigated the case; from a paramedic who responded to the scene; and from the director of the Allegheny County Medical Examiner's Office.

[113][114] Photographs were also introduced as evidence,[113] including photos of exhaustively documented bloodstains, bullet fragments, and shell casings, and police body-worn camera footage was also shown to the jury.

"[115] On June 16, 2023, 50-year-old Bowers was found guilty on all 63 federal charges, including 11 counts of obstructing the free exercise of religious beliefs resulting in death; the jury rendered its verdict after five hours of deliberation over two days.

[119] Three University of Pittsburgh Medical Center physicians (two radiologists and a neurologist) testified about their review of brain-imaging tests (an EEG, PET, and MRI) of Bowers in 2021 and 2022.

"[119] The defense presented evidence of Bowers's lengthy history of serious mental illness, including multiple suicide attempts since his teenage years, an incident in which he "threw flammable liquid on his mother and tried to ignite it" at age thirteen, and three instances of involuntary commitment, the latest in 2004.

[124] On August 26, 2023, Bowers was transferred to the custody of the Federal Bureau of Prisons and placed on death row at United States Penitentiary, Terre Haute.

[94] President Donald Trump, Pennsylvania Governor Tom Wolf, then-Braddock Mayor John Fetterman, and Pittsburgh City Councilman Corey O'Connor released statements about the incident through Twitter.

[133][134] Over 2,000 people, including many from the local Jewish community, protested against Trump's visit to the synagogue site, chanting "words have meaning", and carrying signs with such slogans as "We build bridges, not walls".

[136] On the Friday following the shooting, David Shribman, executive editor of the Pittsburgh Post-Gazette, ran the opening of the Hebrew-Aramaic kaddish, often called the Jewish mourner's prayer, as a full-width front-page headline.

[138] The next year, the Pennsylvania General Assembly passed Act 83 of 2019 to establish the state's Nonprofit Security Grant Fund, a state-level version of the NGSP.

[161] Iranian Minister of Foreign Affairs Javad Zarif offered his thoughts and prayers to the victims of the shooting, and said "Extremism and terrorism know no race or religion, and must be condemned in all cases".

[179] On the evening of the shooting, over 3,000 people gathered at the intersection of Murray and Forbes avenues in Squirrel Hill for an interfaith candlelight vigil; it was organized by students from nearby Taylor Allderdice High School.

[36] The day after the shooting, an interfaith vigil organized by the regional Jewish Federation was held at Soldiers and Sailors Memorial Hall, drawing an overflow crowd estimated at 2,500.

[181] Attended by numerous national and local dignitaries, the event featured several speakers, including the rabbis of the three congregations that occupied the synagogue building, Islamic and Christian clergy, and civic leaders.

[182] Among those in attendance were Bill Peduto, mayor of Pittsburgh; Rich Fitzgerald, Allegheny County executive; Senators Bob Casey and Pat Toomey; Governor Tom Wolf; Naftali Bennett, Israeli Minister for Education and Minister for Diaspora Affairs; Ron Dermer, Israeli ambassador to the United States; and Danny Danon, permanent representative of Israel to the United Nations.

NBC News reported thousands of people around the world attended services in local synagogues, community centers, and college campuses, including Mayor of London Sadiq Khan.

"[212] Among American neo-Nazis and white supremacists, figures such as Richard B. Spencer, Andrew Anglin, and Matthew Heimbach expressed fear that the backlash over the attack could derail their efforts to gain mainstream political acceptance.

[213][214][215] On August 10, 2023, Hardy Carroll Lloyd, a man from Follansbee, West Virginia, was arrested for allegedly making threats towards the jurors and witnesses in Bowers's federal trial on social media and in emails and online comments.

Muslim groups opened a LaunchGood crowdfunding campaign to help pay for the burial of the victims and survivors' medical bills, with the funds to be distributed by the Islamic Center of Pittsburgh.