Robert Bowers, the man accused of shooting 11 worshipers to death at the Tree of Life synagogue on Saturday, sat stony-faced and mostly silent before a US magistrate judge, who ordered him held without bond in the deadliest attack ever on America's Jewish community.
The onetime truck driver, who frequently posted anti-Semitic material online and was described by neighbors as a loner, was charged with 29 federal felony counts and could face the death penalty if convicted.
Prosecutors have said they are treating the mass shooting as a hate crime. The bloodshed heightened a national debate over Trump's inflammatory political rhetoric, which his critics say has contributed to fomenting a surge in right-wing extremism in the United States.
"Yes, words matter," Pittsburgh Mayor Bill Peduto, a Democrat, said during a CNN interview on Monday.
Over the weekend, Trump branded Saturday's shooting an act of pure evil but also angered some by telling reporters the slaying might have been prevented had an armed guard been present at the synagogue.
The White House nevertheless said the president would visit Pittsburgh on Tuesday with first lady Melania Trump to "express the support of the American people and grieve with the Pittsburgh community."
The trip would come just a week before the hotly contested Nov. 6 congressional elections that will determine whether Trump's Republican Party will retain a majority in Congress.
It also will coincide with at least the first two funerals scheduled for the slain worshipers - David Rosenthal, 54, and his brother Cecil Rosenthal, 59.
The Trump administration has rejected the notion he has encouraged white nationalists and neo-Nazis who have embraced him. But a group of local Jewish leaders told Trump in an open letter on Monday he was "not welcome in Pittsburgh until you fully denounce white nationalism."
More than 27,000 people have signed the letter, organized and posted online by the Pittsburgh chapter of Bend the Arc, a Jewish organization devoted to opposing "the immoral agenda of the Trump administration and the Republican Party."
Trump drew bipartisan condemnation last year for saying "many sides" were to blame for violence that erupted during a "Unite the Right" rally in Charlottesville, Virginia, and during a torch-lit march the night before by hundreds of right-wing demonstrators chanting, "White lives matter" and "Jews will not replace us."
Peduto said he believed Trump should wait until all the funerals were held before coming to Pittsburgh. He suggested Trump's visit and the additional security measures entailed would distract from the "priority" of burying the dead.
Tree of Life Rabbi Jeffrey Myers, said, however, on ABC on Monday that the president of the United States was always welcome to visit.
Bowers, 46, is accused of storming into the synagogue in Pittsburgh's heavily Jewish Squirrel Hill section yelling, "All Jews must die" as he opened fire on members of three congregations holding Sabbath prayer services there on Saturday morning.
In addition to the 11 mostly elderly worshipers who were killed, six people, including four police officers, were wounded before the suspect was shot by police and surrendered.
Two of the surviving victims remained hospitalized in critical condition.
"Robert Bowers murdered 11 people who were exercising their religious beliefs," U.S. Attorney Scott Brady said after the Monday's arraignment, adding a grand jury would hear details of the crime within 30 days.
The judge ordered Bowers to remain in federal custody and ruled he was entitled to court-appointed counsel. His next hearing was set for Thursday.
Bowers' arraignment was marked by a heavy security presence that included police officers with dogs and a team of sharpshooters at the federal courthouse in Pittsburgh.
Wearing a blue sweatshirt, gray sweatpants, sandals and white socks, with a crewcut and bald spot, Bowers remained expressionless throughout the brief proceeding.
Bowers said nothing except to give his name, acknowledge he understood the charges against him and that he lacked funds to pay for an attorney. He spoke in a calm voice and signed the papers handed to him with a steady hand.
Only at the end of the hearing when he was wheeled out of the courtroom did Bowers appear unsettled, turning his head in apparent confusion.
According to an affidavit filed in the case by the FBI, three handguns and an AR-15 rifle were recovered at the scene.
The complaint quoted Bowers as saying to one law enforcement officer, in substance: "They're committing genocide to my people. I just want to kill Jews."
He is charged with 11 counts of obstruction of the exercise of religious beliefs resulting in death and 11 counts of using a firearm to commit murder — one count for each worshipper killed. Seven other counts of civil rights and firearms offences stem from the injury of police officers during the assault.