Online, he seemed like a monster, spewing hate and vitriol. In his own life, Robert Bowers was a ghost.

Neighbors rarely saw more than his parked car, occasionally warming his engine on a cold day. To police, he was an unremarkable collection of traffic violations and minor run-ins. High school classmates couldn’t even recall seeing him in the halls.

Authorities charged Bowers on Wednesday in a 44-count indictment, accusing him of federal hate crimes in the grisly shooting that left 11 people dead at a Pittsburgh synagogue. Investigators continued combing through the sparse details of his life for clues to explain his turn to extremist ideology and violence.

In a statement announcing the indictment, Attorney General Jeff Sessions said the alleged crimes “are incomprehensibly evil and utterly repugnant to the values of this nation. Therefore this case is not only important to the victims and their loved ones, but to the city of Pittsburgh and the entire nation.”

Officials say Bowers, 46, of Baldwin, Pa., drove to Tree of Life synagogue armed with Glock .357 handguns and a Colt AR-15 rifle. Inside the synagogue, Bowers expressed his desire to “kill Jews.” Social media posts from an account under Bowers’s name complained that Jews “infest” the country and compared them to “children of satan.”

The hate he allegedly espoused now has many across the city combing through their brief, elusive encounters with Bowers looking for clues they may have missed of the anger and carnage that poured out this weekend.

“He sort of stayed to himself and was unavailable in the community. There were no incidents of hate speech that his friends or people who lived around him knew about,” said Michael Scott, the chief of police in Baldwin, where Bowers lived most recently. “We had no contact with him at all.”

Bowers’s mother, Barbara Bolt, is distraught over the shooting, said Mark Schollaert, pastor of First Baptist Monongahela Church, where Bolt is a parishioner. Schollaert said Bolt had asked him to speak on her behalf.

“She doesn’t condone at all what her son has done,” Schollaert said. “She’s praying for the families of the victims and their friends.”

Schollaert said he met Bowers while presiding over the funeral of Bolt’s father, who died in 2014. He described Bowers as “normal” and said Bowers was a truck driver at the time.

“There was never any unkindness or negativity,” Schollaert said.

Growing up, Bowers spent much of his high school years at his grandfather’s home in Whitehall, Pa., according to neighbors from that time. Scott, the police chief, said that a few of Bowers’s closest relatives also live in Whitehall, a community of modest brick ranchers and split-levels homes.

Those who lived in the area during the 1980s, when Bowers lived there, described it as a mix of blue- and white-collar workers who rode the bus from the top of the hill eight miles to work in downtown Pittsburgh each day.

Bowers took the school bus to Baldwin High School — home of the “Fighting Highlanders” — which he attended from August 1986 to November 1989, according to the Baldwin-Whitehall School District. He left the year before he was to graduate.

Classmate Kathleen Loeffert, now a dentist in Delmont, Pa., said she remembered little about the quiet, reserved teen who lived down her street, except that he often wore a green camouflage jacket to school.

“Western Pennsylvania in the late ’80s, a lot of the boys wore camouflage,” she said.

As an adult, Bowers frequently visited a house on Fieldcrest Drive in Whitehall. Neighbors said the house belonged to a relative of Bowers who lived there with her disabled son, and that Bowers worked as the son’s caregiver. But throughout that time, Bowers rarely left the house.

“He didn’t communicate with me or anyone,” said John Boff, who lived across the street. “He would come out and have a cigarette, stand by a post or sit in a chair, and then go back in.”

A fleeting impression

For much of the 1990s, Bowers hung around Dormont, a working-class suburb in the Pittsburgh metropolitan area.

His address listed in public records for many years was an apartment located above the Potomac Bakery, a fixture of a small-town main street that includes diners, coffee shops, and a gyro and pierogi takeout restaurant.

Neighbors there recall Bowers working at the bakery. The bakery’s owners said in a statement that someone with that name worked at the bakery “more than 16 years ago” but declined to comment further.

During his time in Dormont, local police said, Bowers had five run-ins with the law, including a traffic violation, after somebody found his “lost wallet” and when officers spotted him on the bakery’s fire escape in 1994. There were no arrests, Dormont Police Chief Michael Bisignani said. Dormont police also had contact with Bowers during a 2004 “medical-related issue,” but Bisignani said he could not discuss the nature of the call due to privacy rules.

Neighbors said Bowers worked in recent years as a trucker and that he would often leave for days at a time. According to local traffic records, Bowers holds a valid commercial driver’s license and in 2015 received a ticket for having an improperly marked tractor-trailer.

On the afternoon of April 15, 2015, Bowers pulled an 18-wheeler into a weigh station on Interstate 79, north of Pittsburgh. The rig, registered to PAM Transport, a national hauling company headquartered in Arkansas, lacked a required decal. The driver’s license Bowers provided that day listed an aunt’s address on Fieldcrest Drive as his own. He was fined and paid $403 for the trucking violation, according to district court records. Executives at PAM Transport did not respond to calls and an email seeking comment.

The Pittsburgh Post-Gazette, citing a list of local truck drivers, said Bowers had been affiliated at one point with B. Keppel Trucking, based in the city. Two unions representing truckers in Pittsburgh said they had no record of Bowers being a member. Reached by phone Wednesday, Robert Keppel, the owner of B. Keppel Trucking, declined to comment.

The newspaper also cited archived Internet records that suggested Bowers was a sound man or Web archivist with a long-running local conservative radio show.

In an interview with The Washington Post, Jim Quinn, the host of “Quinn in the Morning,” said he never met Bowers but that Bowers worked as a volunteer for a company hired to run Quinn’s conservative website, “The WarRoom,” in the 1990s.

“As far as I know, I’ve never met the man,” Quinn said in an interview. “I wouldn’t know him if I fell over him.”

Quinn’s brash brand of conservative radio — he reportedly considers Rush Limbaugh a mentor — debuted in 1993, part of a wave of conservative commentary that helped shift the political debate in Western Pennsylvania, which has grown more Republican-leaning over the years. Quinn — who poses on his website with a rifle-shaped cigarette lighter — said he takes on typical conservative topics on his daily program. On Wednesday morning, for example, he discussed President Trump’s proposal to end birthright citizenship with an executive order.

'Ideology or hatred'

In addition to the federal charges, Bowers also faces a criminal complaint filed by the office of Allegheny County District Attorney Stephen Zappala Jr.

Zappala said Wednesday that he has investigators working to assess Bowers’s mental health and other issues that can impact the state’s ability to bring a capital case.

Zappala said federal investigators are in possession of Bowers’s computer and other belongings, and that his staff is interviewing Bowers’s neighbors, co-workers and others to better understand the suspect’s state of mind before the shooting.

“I think we’re going to need about another week before we’re ready to say anything,” Zappala said.

On Tuesday, the Bureau of Alcohol, Tobacco, Firearms and Explosives said that Bowers had legally acquired and possessed the guns found in the synagogue and his home, but the agency issued a clarification Wednesday calling the earlier announcement “premature” and saying that “no determination” had been made. ATF referred further questions to the U.S. Attorney’s Office for the Western District of Pennsylvania, which declined to comment.

The indictment filed on Wednesday states that Bowers wielded four guns inside the synagogue: three Glock .357 handguns and a Colt AR-15 rifle. Other weapons were recovered in his home, officials say.

While elements of Bowers’s background remained a mystery days after the attack, some of his behavior allegedly matched what authorities have observed in other people accused of carrying out mass killings.

The FBI studied dozens of active shootings that occurred between 2000 and 2013 and found that most of those shooters were fueled by a grievance of some kind, an issue that “may not have been reasonable or even grounded in reality, but it appeared to serve as the rationale for the eventual attack, giving a sense of purpose to the shooter.”

Not all of Bowers’s alleged actions matched what the FBI said it saw in earlier attackers. The study found that most of the shooters examined were fueled by grievances related to something that happened to them, while only a handful were driven by “ideology or hatred of a group,” as authorities have suggested was the case with Bowers.

The targets of the grievance vary, said Phillip Resnick, who served as a forensic psychiatrist in cases involving the Oklahoma City bomber, Timothy Mc­Veigh, and the Unabomber, Ted Kaczynski.

“Whether it’s anti-minority, anti-government, anti-technology,” he said, “it’s that grievance that turns into a justification to kill in their minds.”

Academic research on mass shooters, in recent years, has found commonalities among them: They are often rigid, socially isolated and obsessive. Many describe a feeling of persecution by the world.

Rather than seeing themselves as the cause of problems, forensic psychiatrists say, mass shooters project onto others the responsibility for what is wrong in the world.

That sense of grievance appeared to permeate Bowers’s online persona. On the social media platform Gab, a user with Bowers’s name wrote in his bio that “jews are the children of satan.” His banner image was a clear reference to a white-supremacist meme.

The fact that Bowers presented himself so differently online than in person is not surprising, forensic psychiatrist William H. Reid said. In 2014, Reid spent two months interviewing the gunman who killed 12 and injured 70 in a movie theater in Aurora, Colo. He reviewed a thick notebook in which the gunman had sketched out in chilling detail his plan of attack.

“The way we want to present locally to friends or others, it can be very different than the way we present ourselves on paper,” Reid said. “What often happens with someone whose psyche is fluid is they don’t hold in their thoughts very well. So when they write, their inner thoughts just start pouring out.”

Moriah Balingit in New Eagle, Pa., and Mark Berman, Aaron Davis, Katie Zezima, Matt Zapotosky, Devlin Barrett, Julie Tate and Alice Crites in Washington contributed to this report.