Fishmongers' Hall terrorist Usman Khan used cocaine and heroin months before the attack which saw him kill two people, an inquest heard.
Usman Khan stabbed Cambridge University project workers Jack Merritt, 25, and Saskia Jones, 23, at a prison rehabilitation conference at the venue on November 29, 2019.
Toxicology expert Dr Vincent Cirimele said there was evidence that Khan had been exposed to cocaine and heroin between late August/early September and November 2019.
He said the concentration of both drugs was low, indicating either occasional or unique use.
Usman Khan during a 'thank-you' message for a Learning Together event in Cambridge in 2019
Jack Merritt, 25, and Saskia Jones, 23, were killed at Fishmongers' Hall on November 29, 2019