The 28-year-old was out of prison on licence at the time of the attack, in which a man and a woman were killed and three others were injured.
Khan was shot dead by officers after members of the public restrained him. Police declared the attack a terrorist incident as Khan was known to the authorities, having been convicted for terrorism offences in 2012, according to Met Police Assistant Commissioner Neil Basu.
“He was released from prison in December 2018 on licence and clearly, a key line of enquiry now is to establish how he came to carry out this attack,” he said in a statement. The Times reported that Khan’s release from prison last year came after he agreed to wear an electronic tag and have his movements monitored.
Officers are carrying out searches at an address in Staffordshire, where Khan had been living.