Abu Bakr al-Baghdadi led a movement that prided itself on mass killings and indiscriminate violence. His Islamic State ended thousands of lives across Syria and Iraq and galvanised fighters and supporters worldwide to carry out deadly attacks that were intended to horrify.

On Saturday night, Baghdadi killed himself and three of his children during a US special forces raid on his hideout in Syria. Around the world, survivors and families devastated by Isis have been digesting the news.

“Baghdadi died as he lived – a coward using children as a shield,” said Nadia Murad, a member of Iraq’s Yazidi minority who lost much of her family during Isis advances that UN investigators have described as genocide.

Murad was sold into sexual slavery but managed to escape and later won a Nobel peace prize for her campaigns against sexual violence. She said on Twitter she was grateful for the US operation and called for a global fight to bring Isis fighters to justice.

“We must unite and hold [Isis] terrorists accountable in the same way the world tried the Nazis in an open court at the Nuremberg trials,” she said. “It is important not to forget those who suffered at the hands of [Baghdadi] and his militants still need help.”

It is not known exactly how many people Isis and its followers killed. Thousands of civilians – mostly Muslims – were slaughtered across Iraq and Syria, often in large suicide bombings or mass killings. At the height of Baghdadi’s rule, Isis controlled a chunk of land equal in size to Britain. By 2017, it had lost almost all of that territory.

Khalifa Alkhuder, 26, from Aleppo province in Syria, lost family and friends to the group, and spent six months in an Isis prison. He has been working to help identify the remains of people found in Isis mass graves. “The surprise was that we didn’t rejoice as we expected yesterday,” he said from northern Syria.

The US identified Baghdadi’s remains from his DNA within 15 minutes, Alkhuder said, but scores of families across Syria have still not found missing relatives. “Isis is gone and its leader has been killed but people are still waiting to find out the fate of their children.”

He said he had contacted US forces in Syria to ask for DNA kits but had been told they were too expensive. He accused Donald Trump and other world leaders of focusing on other more high-profile goals. “Countries are using our pain for election campaigns,” he said.

The father of Muadh al-Kasasbeh, a Jordanian pilot who was burned alive in a locked cage by his Isis captors in 2015, said news of Baghdadi’s killing left him happy and proud. “This corrupt man, this insect, this virus that spreads throughout the body of not only the Arab nation but also the Muslim nation, who distorted the image of Muslims and Islam,” Safi al-Kasaesbeh told Reuters, describing Baghdadi.

In the US, the mother of James Foley, an American freelance journalist whose beheading by an Isis fighter in August 2014 was broadcast around the globe, said she was grateful to Trump and the forces that found Baghdadi. But Diane Foley also called for justice. “I hope this will hinder the resurgence of terror groups and pray that captured Isis fighters will be brought to trial and held accountable,” she said. “I remain concerned about the dozen Americans held hostage in Syria, including Austin Tice and Majd Kamalmaz. And I ask President Trump to make them, and all American hostages, a priority.”

Mike Haines, the brother of a British humanitarian aid worker, David Haines, who was killed by Isis fighters, said Baghdadi’s death was an important step in the continued downfall of the militant organisation. “However, the poisonous ideology of Daesh has not died with Baghdadi. We must continue to work together to identify and stamp out the threat,” he said, using the Arabic acronym for the group.

After his brother’s death, fearing that innocent Muslims would be blamed or victimised in the aftermath, Haines set up Global Acts of Unity, a campaign promoting unity, tolerance and understanding in schools. “By ensuring our young people know how to stand up to hatred together, we will defeat those who seek to divide us,” he said.

Additional reporting by Nora Hinnawi