London Bridge attacker Usman Khan attended two counter-terrorism programmes that had not been fully tested to see if they were effective, BBC News has discovered.
Khan, who was convicted of a terrorism offence in 2012, killed Jack Merritt, 25, and Saskia Jones, 23, on Friday.
He had completed two rehabilitation schemes during the eight years he spent in prison and following his release.
The government says such programmes are kept “under constant review”.
Three others were injured after Khan launched the attack at a prisoner rehabilitation event inside Fishmongers’ Hall near London Bridge.
Inquests into the deaths of Mr Merritt and Ms Jones will be opened and adjourned at the Old Bailey on Wednesday.
During his time in prison, Khan completed a course for people convicted of extremism offences and after his release went on a scheme to address the root causes of terrorism.
The first course Khan went on, the Healthy Identity Intervention Programme, was piloted from 2010 and is now the main rehabilitation scheme for prisoners convicted of offences linked to extremism.
Last year, the Ministry of Justice published the findings of research into the pilot project which found it was “viewed positively” by a sample of those who attended and ran the course.
However, the department has not completed any work to test whether the scheme prevents reoffending or successfully tackles extremist behaviour.
There has also been no evaluation of the impact of the Desistance and Disengagement Programme, which Khan took part in after his release last year.
Updates from the Cannock Chase Radio News Desk via BBC Stoke and Staffordshire