The suspect was identified as Sudesh Amman hours after he was killed by the police in a "terror-related" stabbing incident on Streatham High Road on Sunday where at least three people were injured, but none were in a life-threatening condition, the BBC said in a report.
He was under active police surveillance at the time of the attack, which the police believe was an Islamist-related terrorist incident.
"No arrests have been made and inquiries continue at pace," the Metropolitan Police said, while Scotland Yard officers continued searching addresses in south London and Bishop's Stortford, Hertfordshire.
Streatham MP Bell Ribeiro-Addy said: "He (Amman) was under surveillance quite soon after being released which begs the question, why was he released so soon?"
Following the attack, Prime Minister Boris Johnson said that his government on Monday would announce further plans for "fundamental changes to the system for dealing with those convicted of terrorism offences".
He said the government had moved quickly to introduce measures strengthening its response to terrorism, including longer prison sentences and more money for police, following the attack at Fishmongers' Hall, near London Bridge, last November.
Amman had pleaded guilty in November 2018 to six charges of possessing documents containing terrorist information and seven of disseminating terrorist publications, according to the BBC report.
One of the manuals Amman admitted owning was one about knife fighting. He was jailed at the Old Bailey the following month for three years and four months.
Amman was first arrested in north London in May 2018 by armed officers on suspicion of planning a terrorist attack.
In response to the attack, Mayor of London Sadiq Khan said: "Terrorists seek to divide us and to destroy our way of life - here in London we will never let them succeed."
( With inputs from IANS )