Westminster terrorist Khalid Masood copied Isis techniques but there was no evidence he was in contact with the terror group, a senior police officer has said.
Deputy Assistant Commissioner Neil Basu revealed more about the investigation into the attack which killed four and injured more than 50 last Wednesday, reports Daily Mail.
Police believe Masood drove up to 120km/h as he ploughed into his victims on Westminster Bridge and the attack took a mere 82 seconds.
He said: "His attack method appears to be based on low sophistication, low tech, low cost techniques copied from other attacks, and echo the rhetoric of IS (Islamic State) leaders in terms of methodology and attacking police and civilians, but at this stage I have no evidence he discussed this with others.
"Whilst I have found no evidence of an association with Isis or al-Qaeda, there is clearly an interest in jihad."
Detectives have also ruled out that Masood was radicalised in prison, saying he converted to Islam a year after being released.
Born Adrian Elms, Masood took his new name in 2005 having served time for possession of a knife.
"In 2005 he changed his name to Khalid Masood," Basu said.
"His last criminal offence was 2003 and he was not a current subject of interest or part of the current domestic or international threat picture for either the security service or CT (counter terrorism) policing.
"I know when, where and how Masood committed his atrocities, but now I need to know why. Most importantly, so do the victims and families."
But Scotland Yard denied claims Masood had been radicalised in prison, following claims from friends and former colleagues who knew him before and after he served time.
Basu, the senior national coordinator for UK counter terrorism policing, added: "There is no evidence that Masood was radicalised in prison in 2003, as has been suggested - this is pure speculation at this time."
The police also appealed for people who were in contact with the killer on March 22 to come forward.
As well as the four people who died in the massacre in the capital on Wednesday, dozens were injured when the terrorist mounted the pavement on Westminster Bridge to deliberately mow down pedestrians and cyclists.
He then crashed his vehicles into railings outside Parliament before getting out of the car and fatally stabbing police officer Keith Palmer.
Four people have died, excluding the attacker who was shot dead, including PC Palmer, Londoner Leslie Rhodes, 75, US tourist Kurt Cochran, 54, and mother-of-two Aysha Frade, 43.
The method used by Masood struck a frightening resemblance to other deadly terror attacks across the world claimed by Isis.
They follow the terror group's advice to their militants to use vehicles as weapons of mass destruction in busy, public areas.
Other deadly vehicle attacks
Wednesday's terror attack in London was the latest in a string of similar incidents across the world where extremists have used vehicles as weapons.
On Bastille Day in the summer of last year, 86 people were killed when a truck was driven through crowds enjoying fireworks in Nice.
Four months later, a copycat ISIS-inspired massacre took place in Germany when a terrorist drove a truck through a Christmas market in Berlin.
Twelve people were killed in the attack on December 19.
This year, a Palestinian lorry driver mowed down and then reversed over Israeli soldiers.
The attack occurred on January 8 and killed four people.
At least one person is feared dead in the Westminster Bridge incident, which comes on the anniversary of another deadly act of terrorism in the name of Islamic State in Brussels which killed 32.
ISIS' propaganda magazine has regularly called on lone wolf attackers to use lorries and vehicles as deadly weapons.
In response to the terror threat, France is in the process of building an 8ft bulletproof wall around the Eiffel Tower aimed at protecting the iconic landmark from potential jihadists.
n the evening of July 14, 2016, a 19-tonne cargo truck was driven into crowds celebrating Bastille Day on the Promenade des Anglais in Nice.
Isis fanatic Mohamed Lahouaiej-Bouhlel was behind the wheel and after exchanging gunfire with police, the Tunisian migrant was shot dead.
Thousands had gathered on the seafront to watch the fireworks that night.
Eighty-six of them died and 434 were injured.
Anis Amri stole a cargo truck and killed 12 people when he drove through a Christmas market next to the Kaiser Wilhelm Memorial Church at Breitscheidplatz in Berlin.
Among the dozen people killed in the Isis-inspired terror attack on December 19, 2016, was the original driver of the truck Lukasz Urban who was found dead with a gunshot wound in the passenger street.
Amri was a Tunisian who had failed to gain asylum status in the country.
He was killed in Milan four days later after an international manhunt.
On January 8 this year, a Palestinian rammed a truck into a group of Israeli soldiers visiting a popular tourist spot in Jerusalem, killing four and wounding 15 people, in a shocking copycat of the Berlin and Nice terror massacres.
Shocking video from the scene shows the driver reversing back over the soldiers, trapping 10under his wheels, during the sickening attack.
Israeli Prime Minister Benjamin Netanyahu alleged the attacker 'supported' the Islamic State group, though he provided no details on what led to the finding.
He said there 'definitely could be a connection' between the attack, which killed four Israeli soldiers, and recent attacks in France and Germany.
A Somali refugee injured 13 people when he rammed his car into a group of people outside Ohio State University in Columbus.
Abdul Razak Ali Artan was shot dead by the first responding OSU police officer and Isis claimed through its Amaq News Agency that he had acted on behalf of the terror group.
After mowing down people in the car, he jumped out of his vehicle and attempted to stab more people.