The suspect who authorities say fired on Republican lawmakers as they played baseball on Wednesday raged against Republican US President Donald Trump on social media and idolised Bernie Sanders, who he viewed as the only politician who understood the working class.
A senior US official named the gunman as James T. Hodgkinson from the St. Louis suburb of Belleville, Illinois. State records showed he was a 66-year-old home inspector.
He died from injuries sustained in a shoot-out with Capitol Hill police who were at the scene in Alexandria, Virginia.
He is believed by investigators to have been a person "of strong views," the US official said, without elaborating.
The Belleville News-Democrat, a local newspaper, posted a photograph of Hodgkinson protesting outside a post office there in 2012, wearing sunglasses and a goatee and holding a homemade placard that read "TAX the Rich."
Hodgkinson was a member of many anti-Republican groups on Facebook including "The Road to Hell Is Paved With Republicans," "Terminate The Republican Party," and "Donald Trump is not my President," a search of what appeared to be his profile showed.
Trump won the US presidential election in November and took office in January. Republicans also control both chambers of Congress.
Trump is a traitor
"Trump is a Traitor. Trump Has Destroyed Our Democracy. It's Time to Destroy Trump & Co." Hodgkinson wrote in a March 22 post on Facebook. His profile picture was a US flag overlaid with the slogan, "Democratic Socialism explained in 3 words: 'We the People.' Since 1776."
His timeline was headed by a cover photo of Sanders, a US senator from Vermont who ran unsuccessfully to be the Democratic Party's presidential candidate last year.
Sanders said on Wednesday that the suspect had "apparently volunteered" on his campaign. He condemned the shooting, saying in a statement that he was "sickened by this despicable act."
Sanders, an independent, ran an insurgent campaign as a progressive populist but was defeated by Hillary Clinton.
One woman who asked not to be named told Reuters that Hodgkinson had contacted her via Facebook as part of a political discussion, but that he subsequently commented on her page that Clinton was a "liar" and a "baby killer."
"I actually blocked him at one point," the woman said.
Neighbour warned him off
William Schaumleffel, one of Hodgkinson's neighbors, recalled how in March he heard gunshots and saw Hodgkinson shooting with a long gun toward woods across a corn field from his yard. "I yelled at him, 'Hey stop shooting over there. There are houses over there,'" Schaumleffel said.
Hodgkinson did not stop, Schaumleffel said, so he filed a report with the sheriff's office.
Hodgkinson's brother, Michael, told the New York Times that, while he was not close to his sibling, he knew he was distraught over Trump's electoral win and went to Washington to protest.
"I know he wasn't happy with the way things were going, the election results and stuff," Michael Hodgkinson said.
Hodgkinson's criminal history included a 2006 arrest on battery charges that were later dismissed, as well as multiple traffic violations, according to state records that identified him as a 1.67-meter man weighing 86 kg, with brown eyes. Most of the infractions were ultimately dropped.
Hodgkinson had been licenced as a home inspector and a real estate appraiser, but did not renew his home inspector licence after it expired last year, state records showed. His incence to appraise real estate expired in 1997.
According to his Facebook profile, Hodgkinson went to Belleville Township High School West and studied flight training at Southwestern Illinois College.
Letters criticising Republicans
The Belleville News-Democrat published several letters he wrote them criticising Republicans, tax policies and income inequality. "I have never said 'life sucks,' only the policies of the Republicans," he said in an August 2012 letter.
A review of Hodgkinson's online activity stretching back several years found that his public posts were almost exclusively about politics, and often critical of Republicans.
Beginning around the summer of 2015, Hodgkinson began expressing enthusiastic support for Sanders' 2016 campaign, and federal records showed he donated $18 to the effort.
"Bernie is the Only Candidate in Decades that Really Cares about the Working Class," Hodgkinson posted on June 13, 2016.