Video has emerged showing terrorist Sudesh Amman, 20, calmly walking down the street moments before he launched his attack on innocent passersby.
CCTV obtained by ITV News shows him wearing a hat and coat and carrying a white bag.
Shortly after the footage was taken, he attacked a man and a woman with a knife he grabbed from a shop, leaving one of them seriously injured.
With 60 seconds of launching his assault, he was shot dead by armed police who were carrying out surveillance on him after his release from prison.
This CCTV was filmed moments before Sunday’s knife attack in Streatham that left two injured.
It shows Sudesh Amman, the attacker, who was later shot dead by counter terror police who were tailing him.
— ITV News (@itvnews) February 5, 2020
The convicted terrorist wore a fake suicide belt during the attack on Streatham High Road, south London, on Sunday.
He had been jailed for possessing and distributing terrorist documents in December 2018, but was freed automatically halfway through his sentence less than a fortnight ago.
He was put under 24-hour police surveillance on his release after it is understood security services regarded him as an ‘extremely concerning individual’.
This afternoon, Metropolitan Police assistant commissioner Neil Basu, head of UK counter-terror policing, warned that the ‘threat is, despite our best efforts, not diminishing’, after a third attack in as many months.
The UK’s terror threat level is currently set at ‘substantial’, meaning an attack is likely. It was downgraded from ‘severe’, the second highest rating, in November, shortly before the London Bridge attack.
Mr Basu said: ‘Police and the security services knew the attacker posed a significant risk and we were, unfortunately, proved right in our decision to place him under surveillance.
‘But with 3,000 or so subjects of interest currently on our radar, and many convicted terrorists soon due to be released from prison, we simply cannot watch all of them, all the time.’
He welcomed plans announced on Monday by Justice Secretary Robert Buckland, who said the urgent legislation was needed to make sure offenders serve two thirds of their sentence before they are considered eligible for release, at which point their case would be considered by a panel of specialist judges and psychiatrists at the Parole Board.
There are 224 terrorists in prison in Britain, with most thought to be holding Islamist extremist views, according to the latest published figures to the end of September.
As many as 50 terrorists could be freed from jail this year, figures suggest.