WASHINGTON • He lived out of his van in the Northern Virginia suburbs and took showers at the YMCA. On Facebook, he posted furious criticism of President Donald Trump and pledged allegiance to Senator Bernie Sanders.
Back home in Illinois, neighbours complained to the police of his practising his shooting near their home.
Shortly after 7am on Wednesday (7pm Singapore time), the police say James Thomas Hodgkinson, 66, opened fire on a baseball field in Alexandria, Virginia, just steps from the YMCA, spraying bullets at members of the Republican congressional team practising there.
An ensuing firefight with the police took Hodgkinson's life.
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The suspect's brother said Hodgkinson was a critic of Mr Trump who was upset over last year's election and intended on bringing his protest to Washington.
But his more immediate motive for the attack remained unclear.
The gunman's brother, Mr Michael Hodgkinson, said: "I know he wasn't happy with the way things were going, the election results and stuff.
"Totally out of the blue," he said, adding that his brother was engaged in politics but otherwise led a normal life.
For much of his adult life, the suspect lived about 90m off a rural road in a well-kept, two-storey home on the outskirts of Belleville, Illinois.
He was a high school wrestler, worked for years in construction and then moved to the home inspection business, starting his own company, JTH Inspections.
He appeared to have taken Mr Trump's victory in November particularly hard, letting a licence on his business lapse that month. And, in late March, the authorities said he relocated to Alexandria, just south of Washington.
Hodgkinson continued to post blistering Facebook assessments of Mr Trump and the Republicans in charge in Washington.
His page was filled with references to Mr Sanders, who has called on Democrats to endorse more progressive politics since losing the race for the party nomination to Mrs Hillary Clinton last year.
In a statement on Wednesday, Mr Sanders condemned violence of any type.
"Let me be as clear as I can be. Violence of any kind is unacceptable in our society and I condemn this action in the strongest possible terms," he said.
Hodgkinson also had run-ins with law enforcement over the years.
In 2006, he was charged with domestic battery, aggravated discharge of a firearm and criminal damage to a motor vehicle after forcing his way into a neighbour's home to find his daughter. The charges were later dismissed.
"He seemed like a loner," said Mr William Euille, a former Alexandria mayor who came to know Hodgkinson during regular morning stops at the YMCA.
Mr Dale Walsh, who identified himself as a friend, said Hodgkinson had been a vibrant presence when he was younger. "He wasn't evil," he said. "I guess he was tired of the politics."