Streatham attacker Sudesh Amman was followed by armed police for 40 minutes before he launched his horrific knife rampage on Sunday – and was then shot dead 60 seconds later.
A surveillance operation was tracking Amman, 20, following his early release from from jail on January 23.
Amman had spent just over a year in prison after being arrested for 13 terror offences, including owning a bomb making manual.
However, despite being followed by armed police, the terrorist was able to get his hands on a knife, which he stole from a shop, and attack two people on Streatham High Road before being shot dead by police.
Authorities are now refusing to explain why Amman was able to get his hands on the blade – despite being trailed by officers – or give any more details on the surveillance operation.
The Metropolitan Police also said the fake suicide vest Amman was wearing was missed by officers monitoring him because it was hidden under his clothes.
Sudesh Amman, 20, from Harrow, fantasised about carrying out a terror attack with a blade or with acid while riding a moped and had been jailed in 2018 – before being released a few days ago
Armed police shot dead extremist Amman after he grabbed a knife from a shop and stabbed a man and a woman in a brutal high-street rampage in Streatham, South London, yesterday
Amman lays dead on the pavement on Streatham High Road after being shot dead by undercover police officers
They confirmed that he had been in a shop on Streatham High Road for 60 seconds before grabbing a knife and sprinting outside.
He then attacked two people, stabbing a man in his 40s in the stomach and a woman in his 50s in the back, before being shot dead by the officers trailing him around a minute after starting his attack.
The Met said in a statement on Monday night: ‘The time from him entering the shop to beginning his attack outside was approximately 60 seconds. Police officers responded, fatally shooting him within approximately 60 seconds of him beginning to attack people.’
‘An operation was launched which included armed surveillance officers. Revealing details of this surveillance operation could undermine police tactics used to investigate terrorists and other criminals across the UK, so it is right that we do not expand on this further at this time.
‘We are confident that this is an isolated incident that has been contained.
Streatham terrorist Sudesh Amman is pictured as a young boy while holding a vacuum cleaner in his living room
Police officers inspect the Sudesh Amman, 19, lying face down on Streatham High Road at around 2pm on Sunday (left) and officers suddenly backing off (right)
The statement added: ‘Armed officers, who were part of a proactive counter-terrorism surveillance operation relating to the attacker, were following him as he left an address in the Streatham area at shortly after 13:20hrs.
‘He then made his way on foot and was observed entering a shop on Streatham High Road shortly before 14:00hrs.
‘From initial witness statements we understand that he stole a knife and ran from the shop as he was pursued by a member of staff.
‘As he ran from the shop, he removed packaging from the knife, and once outside attacked two members of public.
‘The time from him entering the shop to beginning his attack outside was approximately 60 seconds. Police officers responded, fatally shooting him within approximately 60 seconds of him beginning to attack people.’
Amman, 20, was shot dead just days after he was released from prison on January 23.
He had been jailed for three years and four months in December 2018, when he pleaded guilty to 13 counts including possessing bomb-making manuals and knife-fighting guides.
Amman – wearing a hoax explosive vest (circle left) – was shot dead by undercover officers on Streatham High Road just after 2pm yesterday after snatching a blade (circle right) from a shop and slashing a man in his 40s and a woman in her 50s
However, he was automatically released halfway through his sentence, despite fears he still held extremist views.
It is now understood that counter-terrorism bosses decided Amman needed round-the-clock watching by officers, and shortly after this decision surveillance squads were ordered to arm themselves after he was assessed to be even more dangerous than originally thought, sources told the Guardian.
The news comes as Amman’s ex-girlfriend revealed how she lived in constant fear of him, even after they split, because he had urged her to behead her own parents.
Long before the 20-year-old terrorist’s stabbing spree through Streatham, south London, yesterday, he made clear his rampant radicalism to his one-time partner.
She said he would fantasise about slaughtering non-believers with knives and had carefully plotted how to execute such an attack.
But she ended her hellish one-year relationship which cut ’emotional and psychological’ scars after he told her to kill her family.
The horrified ex-girlfriend continued life ‘looking over her shoulder’ – and she has been forced to relive her ‘nightmare’ following Amman’s blade rampage.
The woman, who has asked not to be named, told MailOnline: ‘What Sudesh did was horrible and disgusting. I don’t want anything to do with him or what he has done.
Sudesh Amman kept a notebook in which he wrote that his ‘goals in life’ were: ‘Die as a shuhada’, which means martyr, and ‘go to jannah’, which translates as paradise
Amman is pictured as a boy, shirtless and pulling a face while playing on the pavement (left), and eating food (right)
‘I have tried to move on with my life after what he did the first time. This has affected me really badly.
‘But now after I heard what he did I am angry. I just want to live a normal life. I never really knew him.
‘You never really know someone. Now I just want to be able to walk down the street in peace.’
The ex-girlfriend relived a conversation with Amman, in which he schemed the best way to kill civilians without drawing the attention of the security forces.
According to the Sun, she said he ‘preferred knives’ and told her: ‘If you can’t make a bomb because family, friends or spies are watching or suspecting you, take a knife, molotov, sound bombs or a car at night and attack the tourists (crusaders), police and soldiers of taghut, or western embassies in every country you are in this planet.’
The ex-girlfriend said she felt ‘trapped’ in her year-long romance with Amman, which started well but soon became clear that ‘something was not quite right’.
Mrs Khan said Amman – who is pictured as a youngster in this photograph – was watching fundamentalist paraphernalia online and it led to his arrest
Mrs Khan also issued this picture of her son Amman posing with a BlackBerry mobile phone
In an interview with ITV News, she said: ‘He never hurt me physically, but emotionally and psychologically he did. I felt trapped. I tried to deal with it by myself, but it affected me tremendously.
‘He seemed OK at first, but it quickly became apparent that things weren’t right.’
She went on: ‘Even though it was a long time ago I still feel like I’m having to look over my shoulder’
‘I just live in fear – it shouldn’t’ be like this. But it’s given me some closure that I don’t feel trapped in a situation anymore’
‘It’s really opened my eyes – you think you know a person, but you don’t. People should be careful. I feel hugely betrayed – this was someone I trusted, and now I’ve got to live with this the rest of my life.
‘I haven’t heard from him for a long time, I don’t know what happened to him in prison’
‘I didn’t believe in his ideology, I didn’t condone it, I didn’t agree with it and I never will, but I couldn’t stop it.’
‘The authorities really need to focus on rehabilitation. Offenders like this, with that sort of ideology, if they’re not rehabilitated properly before they’re released, or the penalties are increased then this will just happen again’
‘My tears and heart are with the innocent people affected.’
Meanwhile, the terrorist’s mother revealed how Amman asked for his favourite mutton biryani meal just hours before he was shot dead by police in London.
Haleema Khan, 41, of Dunstable, Bedfordshire, learned about both yesterday’s attack in Streatham and her son’s death from TV news, having spoken to him on the phone earlier in the day when he asked for the meal.
It comes as Mrs Khan revealed three pictures of Amman as a boy – shirtless and pulling a face while playing on the pavement; posing with a neck chain while eating with a fork; and holding a vacuum cleaner.
She described her son as a ‘lovely boy’ as she fought back tears today while telling MailOnline how she felt he was radicalised at HMP Belmarsh in Thamesmead, South East London. The top-security jail has been home to a number of high-profile extremist prisoners, including Lee Rigby killers Michael Adebolajo and Michael Adebowale.
Mrs Khan said Amman had also developed extreme views after looking at Islamist material online. She is now trying to get her son’s body from police as soon as possible to bury him.
Amman lived with Mrs Khan and his five younger brothers in Harrow, North West London, before he was jailed for terror offences at the Old Bailey in December 2018.
A family source said Mrs Khan was ‘disgusted’ by yesterday’s attack, although neighbours said she had been convinced of her son’s innocence even after he was convicted.
Mrs Khan told MailOnline today: ‘He wasn’t even a very devoted Muslim. He got radicalised while he was in Belmarsh Prison (in Thamesmead, South East London).
‘He got into all this (supporting terrorism) on the internet, but when he went to prison something happened to him.’
She said she saw him twice last week in a bail hostel in Streatham, South London, and last on Thursday where he was staying at following his release.
Fighting back tears, Mrs Khan said she had taken him food and that he had not mentioned anything about carrying out a terrorist attack.
Emergency laws blocking the early release of terrorists from prison will be brought in following yesterday’s brutal attack in London, the government announced today.
Justice Secretary Robert Buckland announced plans for new legislation that would stop extremists from being freed from prison until they had served their full sentence unless they had been assessed and cleared by the Parole Board.
A No 10 source said the legislation would be introduced this week ahead of a package of measures expected later this year that could include a beefed-up role for the Parole Board.
Crucially ministers want plans for the law to apply to those already in prison for terror crimes, as well as those jailed in future.