A counter-terror detective has admitted he should have considered the risk posed by the Fishmongers' Hall attacker travelling to London unescorted.
Det Sgt Jon Stephenson said that in hindsight, the decision to allow Usman Khan to attend a prison education event on 29 November 2019, was a risk.
Jack Merritt, 25, and Saskia Jones, 23, were stabbed to death by Khan at the Learning Together event.
Jury inquests are taking place for the pair at London's Guildhall.
Giving evidence, Det Sgt Stephenson said there had been nothing mentioned about Khan's behaviour at a multi-agency public protection arrangements (MAPPA) meeting to suggest that his visit was a risk.
But asked if he accepted he should have raised the issue at a joint police and MI5 meeting just days before the attack, Mr Stephenson said "around risk management, yes".
He added: "I could have raised that point, yes."
Jurors have heard that Khan travelled alone to London with recently purchased knives and wearing a hoax suicide vest.
It was his solo first trip having previously been accompanied by police to a previous Learning Together event.
Police, probation and MI5 were all aware of Khan's planned trip, but none took any measures to mitigate potential risks.
Det Sgt Stephenson, from Staffordshire Police, said: "There had been no recent adverse intelligence since his release.
"He continued to engage with authorities, all the reports appeared to be positive from Prevent [the government counter extremism strategy] and probation, and Learning Together, was deemed by us to be a positive factor in his rehabilitation.
"I am not aware of any objections raised by anybody about what he shouldn't attend."
Jonathan Hough QC, counsel to the inquests, said Khan was a terrorist with a "terrible record in prison".
He asked: "Looking back, do you think you and your colleagues ought to have raised a concern and given some advice on this?"
Det Sgt Stephenson replied: "Yes."
He agreed with Mr Hough that Khan was a "very dangerous man" who was capable of lies and manipulation.
Mr Hough asked: "Did it not occur to you, as a seasoned counter terrorism officer, that sending such a person into the heart of London could pose a serious risk?"
Det Sgt Stephenson replied: "In hindsight".
The inquests continue.