The London Bridge terrorist wrote a poem and a thank-you note to the prisoner rehabilitation programme he later attacked, it has been reported.
The victims were remembered on Monday in services at Guildhall Yard in the City of London and outside the Guildhall in Cambridge, the city where both had studied.
Britain's Prime Minister Boris Johnson, Britain's opposition Labour Party leader Jeremy Corbyn and Mayor of London Sadiq Khan attend a vigil for victims of a fatal attack on London Bridge in London, Britain December 2, 2019.
The ceremony also paid tribute to the emergency services and the people who stepped in to tackle the attacker.
Mr Merritt's girlfriend Leanne O'Brien broke down in tears as she was supported by family and friends at a vigil in Cambridge, while politicians gathered in London to pay their respects.
In an interview with the BBC, Fishmongers' Hall chief executive Toby Williamson, praised the actions of his staff, later adding that Lukasz was stabbed five times during the incident, but continued to help nonetheless.
Johnson has vowed to take steps to ensure people are not released early when they commit serious offences.More news: Health Ministry confirms 24 influenza deaths to date
More news: Evacuation slide falls off USA plane mid-flight
More news: Taylor Swift Talks Acting Career, Song Ownership Amid Scooter Braun Feud
"It's not lenient policies that are to blame, it's the destruction of the probation service that is supposed to monitor and supervise prisoners after release, & rehabilitation services", he said on Twitter.
'A amusing, kind, positive influence' Saskia Jones, 23, has been identified by London's Metropolitan Police as one of the two people killed in a November 29 stabbing attack at London Bridge.
Under the review of released terror convicts, police in the West Midlands said they had arrested a 34-year-old man "on suspicion of preparation of terrorist acts".
"Don't use my son's death, and his and his colleague's photos - to promote your vile propaganda", David Merritt said in a tweet above images of the front pages of right-wing tabloids, the Daily Mail and Daily Express, both of which described a government plan for a "blitz on freed jihadis".
"There are enormous questions to be learnt from this bad event that happened last week and that is, what happened in the prison with this particular individual, what assessment was made of his psychological condition before he was released and also what supervision and monitoring he was under after coming out?" said opposition Labour Party leader Jeremy Corbyn.
"Jack stood against everything you stand for - hatred, division, ignorance", he said. "And a lot of the time these are areas that they have seen people go through the prison system not understanding and they want to do research which will help people".
After searching on Saturday two properties in central England believed to be linked to Khan, police have said they believe he was acting alone and were not seeking anybody else. Police said Monday he had been returned to prison for breaching his release conditions.
On the day of the attack, Khan attended a conference hosted by Cambridge University scheme "Learning Together" at Fishmongers Hall near London Bridge. The group did not provide any evidence.