Merritt, 25, has not been officially named by police but his father has posted a tribute to him on social media confirming his death in the attack.
"R.I.P Jack: you were a handsome spirit who always took the side of the underdog".
Mr Merritt has since deleted his tweets.
Meanwhile members of the criminal justice community said they were "in deep shock" over Mr Merritt's death.
"His open heartedness, his drive and his faith in the redemption of prisoners through education shone out", he added. "He saved lives through his work", barrister Tim Storrie tweeted. One of the most painful things. Merritt and one other person were killed and three others injured.
He said he had "dedicated his life to helping others" and it was "genuinely an honour to have met someone like you".More news: Mexico warns will not allow USA to conduct cross-border armed operations
"David, I knew your son through Learning Together & I loved him to pieces-he was the sweetest, most caring and selfless individual I've ever met".
Khan was also reportedly attending the conference, which was held at Fishmongers' Hall, next to London Bridge.
Mr Merritt later said he was overwhelmed by the messages of condolence and appreciation, writing, "Your kind words mean so much to us".
Ms Jones' family released a statement via the Metropolitan Police, which reads: "Saskia was a amusing, kind, positive influence at the centre of many people's lives".
Mr Rozenberg described him as "a fine young man, dedicated to improving people's lives".
United Kingdom media have reported the 25-year-old was a course coordinator at Cambridge University's criminology institute.
As the confrontation moved from inside the hall to the pavement outside, a throng of people could be seen in videos grappling with Khan.More news: Singapore demands Facebook corrections
Jack Merritt, 25, was named on Saturday as one of those killed in the attack.
Tour guide Stevie Hurst told BBC radio: "Everyone was just on top of him trying to bundle him to the ground".
In 2012, police discovered a plot by his terrorist cell to bomb the London Stock Exchange and Khan was sentenced to 8 years. Khan was automatically released on parole last December, against the advice of the original sentencing judge.
Labour Party Jeremy Corbyn criticised the government's sentencing policies.
Mr Basu said officers had been working "flat out" to try to establish the "full circumstances" of the stabbing.
Armed police at the scene of an incident on London Bridge in central London following a police incident, on November 29, 2019.
Health officials said one of the injured was in critical but stable condition, one was stable and the third had less serious injuries. They are now searching properties in Staffordshire, where the terrorist was said to be living.More news: Ireland Set for ISIS Detainee, Young Daughter to Return from Turkey