The man who rammed his car into a barrier outside the US Capitol had been behaving erratically, his brother said.
Law enforcement officials identified the man as 25-year-old Noah Green, who killed one police officer and injured another in the attack on Friday afternoon.
He was shot dead after emerging from his car with a knife, police said.
His brother Brendan Green told The Washington Post there had been worrying signs about his brother's emotional state in the days before the attack.
On Thursday evening, Noah left his brother's flat in Virginia after falling violently ill, and later sent him a text message saying that he was "just going to go and live and be homeless", Mr Green told the Post.
“Thank you for everything that you’ve done. I looked up to you when I was a kid. You inspired me a lot.”
Mr Green said his brother had moved in with him two weeks earlier, after calling to ask for help.
He was crying and said he was "in a really bad situation and in really bad shape", Mr Green said.
About two months earlier, Noah travelled to Botswana from Indianapolis, Indiana, after repeatedly claiming that his flat was being broken into, his brother said.
Mr Green said that while in Botswana, his brother told him that his mind was telling him to take his own life and that he underwent surgery at a hospital after jumping in front of a car.
Noah's erratic behaviour appears to have begun in 2019, while studying at the Christopher Newport University in Newport News, Virginia.
He accused fellow members of the university's American football team and roommates at the university of drugging him with Xanax.
In a post on his Facebook page on March 17, he said his life had been on the “right track” before becoming affected by drugs he was “unknowingly” taking – an apparent reference to the alleged incident at the university.
He wrote that “these past few years have been tough, and these past few months have been tougher”.
“I have been tried with some of the biggest, unimaginable tests in my life. I am currently now unemployed after I left my job partly due to afflictions, but ultimately, in search of a spiritual journey,” he said.
Flags at half mast
President Joe Biden said that he and his wife were heartbroken to learn of the attack and expressed condolences to the family of William Evans, the officer killed in the attack. Mr Biden directed flags at the White House to be lowered to half mast.
The crash and shooting happened at a security checkpoint near the Capitol typically used by senators and staff on weekdays, though most were away from the building for the current recess.
The attack occurred about 90 metres from the entrance of the building on the Senate side of the Capitol. One witness, the Rev Patrick Mahoney, said he was finishing a Good Friday service nearby when he heard three shots ring out.
The Washington region remains on edge nearly three months after a mob of insurrectionists loyal to former president Donald Trump stormed the Capitol as Congress was voting to certify Mr Biden’s presidential win.
Five people died in the January 6 riot, including Capitol officer Brian Sicknick, who was among an outnumbered police force trying to fight off the intruders seeking to overturn the election result.
Authorities installed a tall perimeter fence around the Capitol and restricted traffic along the roads closest to the building, but they had begun reverse some of the emergency measures. Fencing that prevented vehicular traffic near that area was recently removed.
Mr Evans was the seventh Capitol Police member to die in the line of duty in the department’s history, said the Officer Down Memorial Page, which tracks deaths of law enforcement.
In addition, two officers, one from Capitol Police and another from Washington’s Metropolitan Police Department, died by suicide following the January 6 attack.