The brother of a terrorist who killed three people in a park in Reading rang police the day before the attack, warning he "could harm himself or others", an inquest has been told.
Khairi Saadallah stabbed to death three men who were meeting in Forbury Gardens, during a brief relaxation in lockdown rules in the middle of the COVID-19 pandemic.
James Furlong, Joseph Ritchie-Bennett and David Wails were killed and three others injured during a 30-second rampage on 20 June 2020.
Saadallah, who was handed a whole life tariff in 2021, had viewed material on the September 11 attacks and was heard yelling "Allahu Akbar" [god is great] and "God accept my jihad".
At an inquest into the deaths, Saadallah's brother, Aiman, said Saadallah had visited him on the afternoon before the attack and told him he had "left me something to remember him by".
"He asked if he could have a shower and asked me for a prayer mat. Instead of praying he had a joint," he said in a statement.
"He told me about a movie scene in which he was surrounded by jihadists with a bomb strapped to his chest. He said he was going to heaven and there were virgins there waiting for him.
"I said it was not funny. I lost patience and went upstairs."
Later, Aiman, a care worker in his mid-30s, said Saadallah showed an "immediate change to an angry man", adding: "I had never seen him like this before." The brothers had lived together for around a year.
Aiman added: "I rang the police and said he could harm himself or others although I did not believe he would hurt others."
Officers visited Saadallah that evening but he dismissed concerns about him, the inquest heard.
After the attack, Aiman found that Saadallah had used razor blades to shave off his body hair when he had a shower, described by police as part of a "ritual cleansing".
Michael Haynes, a counsellor who worked with Saadallah on drug, alcohol and mental health issues, said he had struggled to get help for Saadallah.
He said Saadallah described himself as a "boy soldier" who had fought in the Libyan civil war against Colonel Gaddafi in 2011.
In a statement, Mr Haynes told the inquest: "He calls himself a boy soldier. I don't know how old he was, but probably 15 years old.
"He drove trucks, he saw lots of death, and when Colonel Gaddafi was ousted these people turned out to be Muslim fundamentalists.
"Because Khairi didn't grow his beard and all the rest of it, they started picking on him. He got an electric shock, tortured and a bloke firing in a darkened room where Khairi was and other stuff."
Saadallah arrived in Britain in around 2015, claiming asylum, and lived initially in Manchester where he suffered from mental health problems, became homeless and got involved with a Somalian gang who attacked him with hammers, leaving scars on his head.
His father was an antiques dealer who was said to be very successful and "had a lot of money" until he fell out with the Gaddafi regime.
His mother was described as a doctor, possibly a psychiatrist, but the couple had split up and lived in different cities in Libya.