Rachid Redouane

On 7 May 2019, an inquest into the deaths of the victims opened at the Old Bailey in London. Chief coroner Mark Lucraft QC and people related to the dead gave accounts of what happened and who they had lost. The inquest concluded on 16 July 2019 that all three attackers had been lawfully killed.

On 3 June 2017, a terrorist vehicle-ramming and stabbing took place in London, England. A van was deliberately driven into pedestrians on London Bridge before crashing on the south bank of the River Thames. Its three occupants then ran to the nearby Borough Market area and began stabbing people in and around restaurants and pubs. The attackers were Islamists inspired by Islamic State (ISIS). They were shot dead by City of London Police officers and were found to be wearing fake explosive vests. Eight people were killed and 48 were injured, including members of the public and four unarmed police officers who attempted to stop the assailants.

In March, five people were killed in a combined vehicle and knife attack at Westminster. In late May, a suicide bomber killed 22 people at an Ariana Grande concert in 2017 at Manchester Arena. After the Manchester bombing, the UK's terror threat level was raised to "critical", its highest level, until 27 May, when it was lowered to severe.

At 21:58 BST (UTC+1) on Saturday 3 June 2017, the van was identified to have travelled south across London Bridge, and returned six minutes later, crossing over the bridge northbound, making a U-turn at the northern end and then driving southbound across the bridge. It mounted the pavement three times and hit multiple pedestrians, killing two. Witnesses said the van was travelling at high speed. 999 emergency calls were first recorded at 22:07. The van was later found to contain 13 wine bottles containing flammable liquid with rags stuffed in them along with blow torches.

Butt was part of an al-Muhajiroun campaign in 2015 to intimidate Muslims who planned to vote in the UK general elections of that year, on the basis that it was forbidden in Islam. He was known for holding extreme views, having been barred from two local mosques. He appeared in a 2016 Channel 4 Television documentary The Jihadis Next Door, which showed him arguing with police over the unfurling of an ISIL black flag in Regent's Park. According to a friend, he had been radicalised by the YouTube videos of the American Muslim hate preacher Ahmad Musa Jibril. Butt was known to have taken drugs before he became radicalised. After radicalisation, Butt started to stop his neighbours on the street and ask them whether they had been to the mosque.

The New York Times said that Butt and his brother were part of the UK government's Prevent programme, which aims to stop people from becoming terrorists, and which reports suspected radicals to police programmes. At the time of the attack he was on police bail following an allegation of fraud, though the police had intended to take no further action due to a lack of evidence. He had previously been cautioned by police for fraud in 2008 and common assault in 2010.

Butt had worked for a man accused of training Mohammad Sidique Khan, the leader of the July 2005 London bombing. The police and MI5 knew of Butt and he was investigated in 2015. The investigation was later "moved into the lower echelons", and his file was classed low priority.

Zaghba (born 1995 in Fez, Morocco) was at the time of the attack living in east London where he worked in a fast food outlet. He also worked at an Islamic television channel in London. Zaghba was born to a Moroccan Muslim father and an Italian Catholic Christian mother who had converted to Islam when she had married. Zaghba had dual Moroccan and Italian nationality. When his parents divorced, he went to Italy with his mother. In 2016, Zaghba was stopped at Bologna Guglielmo Marconi Airport by Italian officers who found ISIS-related materials on his mobile phone; he was stopped from continuing his journey to Istanbul. Italian authorities said Zaghba was monitored continuously while in Italy and that the UK was informed about him. Giuseppe Amato, an Italian prosecutor, said "We did our best. We could just monitor and surveil ... [Zaghba] and send a note to British authorities, that's all we could do and we did it. Since he moved to London, he came back to Italy once in a while for a total of 10 days. And during those 10 days we never let him out of our sight."

Butt (born 20 April 1990) was a Pakistan-born British citizen whose family came from Jhelum. He grew up in Britain, living in Plaistow. He had a wife and two children. Neighbours told the BBC that Butt had been reported to police for attempting to radicalise children; he had also expressed disgust at the way women dressed. He was known to police as a "heavyweight" member of the banned extremist group al-Muhajiroun. A BBC interviewee said he had a verbal confrontation with Butt in 2013 on the day after another Al-Muhajiroun follower had murdered Fusilier Lee Rigby.

Redouane (born 31 July 1986) claimed to be either Moroccan or Libyan, a failed asylum seeker to the UK, whose application was denied in 2009, and not previously known to police. Redouane worked as a pastry chef and in 2012 he married an Irish woman in a ceremony in Ireland. He beat and bullied his wife. She eventually divorced him after he tried to force his extremist beliefs on her. He used to drink alcohol. He lived variously in Rathmines, a suburb of Dublin, also in Morocco and the UK. According to his wife, Redouane was most likely radicalised in Morocco. Later the couple stayed in the UK on an Irish residency card where they had a daughter in 2015. The couple separated in 2016. At the time of the attack, he was living in Dagenham, East London.