The terrorist in the Arsenal shirt who carried out the London Bridge atrocity was under police investigation at the time of the attack.
Police today named two of the three attackers as Khuram Butt, 27, and Rachid Redouane , 30.
It emerged that Butt, a former security site guard, was known to the police and MI5 who opened an investigation into him in 2015.
A few months later, detectives received a call from a concerned member of the public on their anti-terrorism hotline with information about his extremism.
But inquiries established no intelligence or evidence to suggest terrorist activity or that he was planning an attack, according to assistant commissioner Mark Rowley, the UK’s top counter-terrorism officer.
Khuram Butt was named today as one of the three terrorists 
He was shot dead by police after massacring seven 
Butt’s case was moved into the “lower echelons” of the 500 most active counter-terrorism investigations.
Mr Rowley said: “All the work done has never provided any evidence or intelligence of attack planning or other serious offences, consequently as time went on prioritisation of that operation moved and was currently in the lower echelons.”
But the Mirror can reveal that Butt had links to notorious ISIS executioners, dubbed “Jihadi Sid” and the “Jihadi Giant”, which are now being probed by security services.
A scene from the C4 documentary 
Butt was a British citizen born in Pakistan
One of Butt's last WatsApp messages
Butt, a British citizen born in Pakistan, was named as one of the three attackers along with Rachid Redouane, who claimed to be Moroccan-Libyan, who was unknown to police.
Both attackers were of Barking, east London, though it is not known how they knew each other.
Along with a third unnamed accomplice, the pair ploughed a hired B&Q Hertz van into pedestrians on London Bridge before launching a stabbing rampage, killing seven and injuring 49 on Saturday night.
WHO IS KHURAM BUTT? ATTACKER SEEN IN CHANNEL 4 DOCUMENTARY ABOUT JIHADIS
Butt, an Arsenal fan who spoke with a London accent, had previously worked for the London Underground and KFC as an office manager.
He claims on a CV obtained by the Mirror that he had worked as a security guard and held a Home Office approved SIA Licence issued last year, while he was under investigation.
A spokesman for the Home Office declined to comment.
Rachid Redouane was another attacker named 
Locals near his home in Barking, east London, claimed to have reported him twice to the counter terror hotline after becoming alarmed at his radicalisation over the last two years.
One female neighbour said: “He didn’t like it when I was out and about. He didn’t like women.
"I think he thinks they should be suppressed at home. Last week he had a barbecue and he said ‘it’s a no-women zone’.”
Locals also claimed he had previously been ejected from a local mosque for berating an Imam for encouraging worshippers to vote in the 2015 General Election.
A relative claimed he had boasted of wanting to fight in Syria, but it is not known if he travelled ot the war-torn country.
Butt boasts on his CV of his “ability to work under intense pressure whilst managing multiple tasks” and claims he was “a strong team player with extensive communication skills”.
He also claimed to be “adept at communication with a variety of people effectively and relaxed in tentative situations,” was a qualified first aider and a “motivated, zealous and trusted individual with the drive to make a difference and improve, in any given environment.”
On the top of his application he stated how he “fights tooth and nail to achieve the best results for the business, while keeping himself focused and balanced”.
The father of two children, one a baby and the other aged around three, was a supporter of the banned Islamist group al-Muhajiroun whose leader Anjem Choudary has been linked to the recruitment of more than 100 British terror suspects.
A man being taken away from the F1 Tyre Premises on the A13 which anti terror police raided in the early hours of today 
A shirtless man being led away from Caledon Road in East Ham following a raid by anti-terror police this morning 
Married Butt was reportedly spotted last month urging people in east London not to participate in the general election.
He also used the name Abu Zaitun and was known as “Abs” by friends at the gym where he trained near his home in Barking, East London.
Redouane, 30, also used the name Rachid Elkhdar, claiming to be six years younger.
Inquiries are ongoing to confirm the identity of their accomplice, Mr Rowley added.
He refused to say when the investigation into Butt was downgraded, saying: “It’s not a black and white issue but over a period of time the operation has fallen to the lower echelons.”
The terrorists' van lies abandoned on the street
Mr Rowley said he had “seen nothing yet” to indicate that a “poor decision has been made”.
Talking about the three men, he added: “Work is ongoing to understand more about them, their connections and whether they were assisted or supported by anyone else.”
Mr Rowley refused to discuss how the two men met .
Of the seven women and five men arrested since the attack, a man and a woman have subsequently been released.
Security services are probing links between Butt and notorious ISIS executioners, dubbed “Jihadi Sid” and the “Jihadi Giant”.
Bouncy castle salesman Siddhartha Dhar and 6ft 6ins Mohammed Reza Haque were both members of the banned extremist group al-Muhajiroun before they fled the UK to Syria.
Butt appeared in a Channel 4 TV documentary last year called ‘The Jihadis Next Door’ about British jihadists where he was filmed unfurling an ISIS-style flag in London’s Regent’s Park.
Dhar, who changed his named to Abu Rumaysah, also featured in the programme alongside firebrands Abu Haleema and his friend Mohammed Shamsuddin.
Jihadi 'Sid' was believed to have know Butt
Haleema had contact with a teenage jihadi who wanted to carry out a beheading in Australia, while Shamsuddin was an associate of Islamic cleric Anjem Choudary and joined a radical group after meeting hate preacher Omar Bakri.
There is no suggestion Shamsuddin or Haleema had any involvement in Saturday’s attack.
Haque, 36, from Bethnal Green, east London, was a former bodyguard for Anjem Choudary.
He was already fighting in Syria when Dhar, skipped bail and joined ISIS in September 2014.
Rachid Redouane, 30, claimed to be of Moroccan and Libyan descent - and was unknown to police.
The former pastry chef was unmasked via an Irish identity card found in his pocket after he was gunned down by armed cops.
His former partner, Charisse O’Leary, 38, who formerly used his surname, is among those arrested by terror police on Sunday morning.
6ft 6ins Mohammed Reza Haque is also believed to have been an associate 
The couple married five years ago and have a one-year-old daughter.
Friends told The Mirror how their “mismatched” relationship soured following the birth, leading to a split around nine months ago.
But Charisse’s neighbour Kieran Dunn, 24, claimed the terrorist visited his daughter just hours before the London Bridge attack.
Kieran said: “She married him and chucked him out not long ago.
“He came back [to Charisse’s flat] on Saturday night and checked out of the flats at 7.30pm.”
The third suspect in the attack has not been named by police.
In another day of dramatic developments, armed police today carried out two separate dawn raids on properties in Dagenham and Newham.
The former swingers club raided in Dagenham 
Anti-terror cops raided a former swingers club in the hunt for evidence today in connection with the London Bridge attack.
A dozen armed officers using stun grenades were heard bursting into a house in Dagenham, east London, in the early hours.
Residents were awoken by a loud bang and car alarms were set off one resident said it sounded like there was gunshots as they entered the run down property connected to a garage called F1 Tyres which was previously a swingers club.
A property in nearby Newham, east London was also raided at 4.30am by police using an explosive charge to gain entry.
Six people were led from both properties by police but they are not understood to have been formally arrested.or