The Streatham terrorist shot dead by police after a stabbing spree first became known to the authorities after attacking fellow pupils at his school, an inquest has heard.
The inquest into the death of terrorist Sudesh Amman, 20, began at the Royal Courts of Justice on Monday morning.
The coroner, High Court judge Mr Justice Hilliard, said Amman was shot by armed police in Streatham High Road in south London on Sunday Feb 2 2020 after he stabbed and injured two people in an "apparent terror attack".
Amman, originally of Harrow, north-west London, had been under surveillance following his release from HMP Belmarsh 10 days earlier having been jailed for terror offences.
Detective Superintendent Dominic Murphy, senior investigating officer at the Metropolitan Police, said Amman had been referred to children's services during his time at school between 2012 and 2016 following "concerns over his mental health".
Giving evidence at the inquest into Amman's death on Monday, Mr Murphy said he had come to the attention of police in 2016 after he had attacked pupils at his school. He was later convicted for threatening people with a weapon in a public place.
Profile: The Streatham terrorist Sudesh Amman
Mr Justice Hilliard said Amman was born on December 20 1999, and was arrested in May 2018 on suspicion on terror offences.
He was later jailed for 40 months for 13 counts of obtaining and distributing material used for terrorist purposes, and was released automatically on January 23 2020.
The coroner said Amman served his sentence at Belmarsh, adding that there was intelligence he "retained extremist views throughout that time and there were concerns about his release into the community".
After his release, Amman was required to live at a probation hostel in Streatham, with conditions such as a tag and curfew.
Amman was under day-time surveillance by plain clothes officers between January 24 and 28 amid concerns he might commit another offence, and on January 29 a decision was made to allow those officers to carry firearms.
Two days later, Amman was seen looking at knives in a shop and purchasing items that could be used to create a hoax suicide belt, the inquest jury heard, after which it was decided to put Amman under 24-hour surveillance.
Mr Murphy said surveillance operations had been stepped up after Amman was observed entering a number of shops and making suspicious purchases in Poundland.
Amman was reported to have bought a roll of brown tape, a roll of aluminium foil and three bottles of Irn Bru at the shop.
"We have, through experience on previous incidents, (found) that people have made fake suicide vests with similar purchases," Mr Murphy told the inquest.
He added a further review had been undertaken, and from Saturday February 1 the armed officers would carry out "round the clock" surveillance with additional support from uniformed armed police and an arrest team from the Met's SO15 team.
What happened during the Streatham attack?
The coroner described how Amman was seen leaving his hostel on the afternoon he struck, walking towards Streatham High Road at around 1.25pm.
The coroner said: "By 1.50pm, he (Amman) was walking very slowly, he had a white bag across his chest.
"He was under surveillance by four officers on foot, and other officers were in vehicles on a surrounding road.
"At 1.57, Mr Amman entered a general shop ... which sold, amongst other things, knives."
Inquest jurors were shown images of Amman on the afternoon he struck, taken under covert surveillance.
He was seen wearing a camouflage jacket and a red hood and a beanie hat, with grey traditional dress underneath his jacket. He was carrying a white JD Sports bag across his torso.
Mr Murphy told the inquest Amman was under surveillance from nine officers - one on a motorcycle, some in cars, and some on foot.
He told the inquest: "The officers reported he was walking very slowly, apparently aimlessly."
He said an anonymous surveillance officer went towards the shop entrance, just as Amman grabbed a 20cm kitchen knife from a display and ran with it from the store.
Mr Murphy said Amman had been inside the Low Price Store for "less than a minute" but had snatched a kitchen knife from a display before running outside.
"He was only inside for less than a minute," he told the inquest.
"While he was inside he then took a kitchen knife from the display in the shop and then ran from the shop.
"As he left the shop he was tearing the knife out of the packaging."
Jurors were shown a picture of the knife stolen by Amman, which was covered in bloodstains.
The officer, known only as BX87, then ran after Amman. The coroner said Amman then began stabbing members of the public.
He said: "As he ran and within a few seconds, Amman stabbed a lady in the back outside the White Lion public house.
"A few seconds later while still running, he stabbed a man by Cash Converters, in the right side of his torso."
The coroner said a second officer, known only as BX75, also joined the pursuit of Amman and shot at him.
The shot shattered a shop window, and Amman turned to face the two officers while still holding the knife, during which both officers then opened fire.
The inquest jury heard Amman suffered wounds in the neck and abdomen, and was pronounced dead at 3.24pm.
There was a gap of 62 seconds between when Amman fled the shop with the knife, and being fatally shot.
A suicide belt he was wearing was later found to be a hoax.
The coroner warned inquest jurors that some of the evidence may be graphic in nature.
The coroner opened the inquest hearing with a brief summary of the circumstances surrounding Amman's death.
He said: "The inquest concerns the death of Sudesh Amman.
"He died on February 2 last year after having stabbed two people in an apparent terror attack and then having been confronted and shot by armed police surveillance officers."
He said any death involving people killed by police would result in an inquest, held before a jury.
Why was Amman arrested in the first place?
Mr Murphy said Sudesh Amman was arrested in May 2018 on suspicion of preparing and engaging in acts of terrorism resulting from a Met Police investigation.
Amman was identified as the user of a Telegram instant messaging channel with the username @strangertothisworld and had posted extremist material and imagery.
Jurors at the inquest heard that further extremist material was found on Amman's computer, including a recipe for making explosive devices.
Amman's time in prison - and the hand-written Islamic State notes
Mr Murphy said that after being convicted of engaging in and disseminating terrorist material, Amman was sent to Belmarsh prison.
He said Amman believed he had gained "celebrity status as the result of being a convicted terrorist".
Mr Murphy told the inquest that a search of Amman's prison cell found some
hand-written notes in Arabic that "appeared to show loyalty" to so-called Islamic State.
He also showed signs that he had not reformed as late as January 3 2020, three weeks before his release into the community.
Mr Murphy said: "He told another prisoner he was 'not finished with these non-believers yet', which was a direct quote."
Mr Murphy said police were so concerned about Amman that they asked the prison governor to keep him in custody past his automatic release date.
But the request was turned down because the offence Amman committed could not justify an extension of his sentence, the inquest heard.
Eleven jurors have been sworn in for the inquest, which is listed to last for up to three weeks.