One of those killed in the carnage of the London Bridge attack was law and criminology course leader Jack Merritt, described as someone always on the side of the underdog.
The 25-year-old, who worked at the University of Cambridge's criminology department, lost his life at an event underpinned by the belief that every one of us who does wrong is capable of redemption.
But among those ex-offenders attending the Fishmongers' Hall Learning Together event was the man who killed him - as well as other former criminals who came to the assistance of the injured and tried to stop the attacker.
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Jack Merritt, who had attended Hill Road Sixth Form in Cambridge, was the course co-ordinator for Learning Together, described as "bringing students in Higher Education & Criminal Justice institutions together in transformative learning communities".
As part of the programme, students based at the University of Cambridge and students based in prison studied together on university-level courses.
The aim was to form connections that "make society more inclusive and safer by reducing reoffending".
Merritt's father David, also from Cambridge, described his son as "a beautiful spirit who always took the side of the underdog" and who believed deeply in the concept of prisoner rehabilitation.
He added on Twitter: "My son, Jack, who was killed in this attack, would not wish his death to be used as the pretext for more draconian sentences or for detaining people unnecessarily.
"Jack spoke so highly of all the people he worked with and he loved his job."
Jack had previously studied law at the University of Manchester and went on to undergo further studies at Cambridge. A photograph on his social media pages shows him smiling, champagne bottle in hand, on one of the main thoroughfares in Cambridge.
Just a few weeks before he was killed, he was holidaying in Seville, Spain, with girlfriend Leanne O'Brieen to celebrate his birthday. He wrote on social media: "Thanks @leanneobrieen for an ace surprise birthday weekend. Living the dream."
Mr Merritt Snr, who describes himself as "an average, pragmatic left-leaning atheist", was critical of recent cuts in front line police officers and in the budget of the prison and probation services, which he said had "been decimated by cuts since 2010".
Serena Wright, a colleague of Jack Merritt, described him as "the sweetest, most caring and selfless individual I've ever met,'' adding on Twitter: "I loved him to pieces. The warmest heart, always with time for anyone. Completely irreplaceable - I will mourn his loss greatly and honour his memory."
Neighbours near the Merritt family home last night paid tribute to Jack, describing him as "such a fine young man" who "devoted his life to helping others less fortunate than himself."
Dawn Marr, 80, who used to babysit him and younger brother Joe, said: "This is tragic. I just can't believe it and I'm totally shocked. He was such a fine young man and his father was very proud of him."
One of the most upsetting among the blizzard of images taken by passers by of the London Bridge attack showed a severely injured woman being carried in a tarpaulin by four police officers.
Police said a woman was also killed in the attack, along with another dozen injured.
The London Bridge attacker, Usman Khan, was tackled by ex-offenders who had been invited to the conference on rehabilitation after he started "lashing out", it has emerged.
Khan had previously participated in Cambridge University's Learning Together prisoner rehabilitation programme but had showed "no cause for concern".
According to the source, all those involved in tackling Khan, with the exception of the man reported to be a Polish chef, were ex-offenders.
They, along with Khan, had been invited to attend the conference at Fishmongers' Hall after having previously participated in the programme.
It is understood that Khan started "lashing out" in a downstairs room of the hall but was grabbed by the conference-goers and bundled out of the front door as he tried to go upstairs. From here he was chased and bundled to the floor, where he was shot and killed by armed police officers.