As news came that Islamic State executioner ‘Jihadi John’ had "with a high degree of certainty" been killed by an American drone attack, family members of his victims spoke of their "instant sense of relief".
The masked assassin, real name Mohammed Emwazi, is thought to have taken at least five Western lives, but is also linked to the death of at least one Japanese journalist.
Emwazi was first seen in a video in August 2014 which showed the beheading of US journalist James Foley. He had his face covered, but soon became Islamic State's (IS) poster-boy for terror. He later featured in beheading videos, including those in which UK hostages Alan Henning and David Haines were killed and American journalist Steven Sotloff, aid worker Abdul-Rahman Kassig and Japanese journalist Kenji Goto were murdered.
David Haines' daughter Bethany told Sky News: "After seeing the news that 'Jihadi John' was killed I felt an instant sense of relief, knowing he wouldn't appear in anymore horrific videos.
"He was only a pawn in Isis's stupid game but knowing it's over that he's finally dead still hasn't sunk in. As much as I wanted him dead I also wanted answers as to why he did it, why my dad, how did it make a difference."
Emwazi was the target of an operation around Raqqa. Intelligence has yet to confirm whether he was killed in the attack but an unnamed senior source told Fox News: "We are 99% sure we got him." The BBC quoted an official saying they believed "with a high degree of certainty" he was dead.
His victims were:
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Foley was abducted while working as a photojournalist in Syria in 2012 and was the first western hostage beheaded by Emwazi.
The American, 40, and his British colleague John Cantlie, were said to have earlier been subjected to "weeks and weeks" of torture.
The pair twice attempted to escape from their makeshift prison. On the second try Foley had climbed over a wall and was waiting for Cantile to follow when they were spotted by a guard. Instead of fleeing alone, Foley instead surrendered.
He was executed in August 2014, supposedly as retribution for American airstrikes in Iraq. A video of Foley's death also showed British hostage Steven Sotloff, who was thought to be Emwazi's next victim.
Cantile is believed to remain in captivity.
Foley's family said Emwazi's death offered them no comfort.
In a statement to ABC News his parents said, "this huge effort to go after this deranged man filled with hate -- when they can't make half that effort to save the hostages while these young Americans were still alive. It's unfortunate that the government doesn't get it.
"They think it gives us solace, but it doesn't."
Steven Sotloff was beheaded a month later in September 2014.
The 31-year-old freelance journalist from Florida was made to read a statement condemning America's foreign policy in Iraq before his decapitated body was shown on screen.
In the video, Scotloff, who was kidnapped in 2013, said: "Obama, your foreign policy of intervention in Iraq was supposed to be for the preservation of American lives and interests, so why is it that I am paying the price of your interference with my life? Am I not an American citizen?
"You've spent billions of US taxpayers' dollars and we've lost thousands of our troops in our previous fighting against the Islamic State, so where is the people's interest in reigniting this war?"
His killer, thought to be Emwazi, then said: "I'm back, Obama, and I'm back because of your arrogant foreign policy towards the Islamic State, because of your insistence on continuing your bombings despite our serious warnings.
"Just as your missiles continue to strike our people, our knife will continue to strike the necks of your people."
According to The Telegraph, a spokesman for the Sotloff family said after his murder: "The family knows of this horrific tragedy and is grieving privately."
Just like in the video of Foley's execution, the Islamic State again showed the next hostage destined for death - David Haines.
Father-of-two David Haines was the first Briton to be murdered by Islamic State jihadists.
The 44-year-old former RAF engineer, who was working for an aid agency in Syria, was abducted in March 2013 near the Atmeh refugee camp on the Turkish border with the northern Syrian province of Idlib.
The whereabouts of Haines, who was born on Humberside but grew up in Perth, was unknown until he appeared in an IS video last September.
In a video of his killing, the terrorists also threatened to murder Alan Henning, a 47-year-old from Manchester who was captured in Syria in 2013.
The Daily Telegraph subsequently learnt that Haines, who has 17-year-old daughter by his first wife Louise and a five-year-old daughter, Athea, by his second wife Dragana, helped to devise a children's story with two fellow French hostages who survived to tell the tale and who paid tribute to their "amazing" friend.
His wife earlier this year said that she had not yet told Athea what had happened to her father.
She had also expressed hope that her husband's killer be caught alive because if he was killed, it would be deemed an "honourable death" which she said would be the "last thing" she would want for him.
"It's a cowardly act to behead someone who has his hands tied behind his back, who is kneeling. And you're not a human being, you must be a monster to do something like that," she said, according to The Telegraph.
In an interview broadcast on BBC Radio Scotland in January, his brother, Mike Haines said: "The image on David's face when he was witnessing Steven's murder – it wasn't horror at what was approaching him, it was horror at what was happening to Steven.
"In the deep, dark nights when I am not sleeping, I see that look on his face."
Alan Henning, who volunteered to join a humanitarian convoy bringing aid to the people of Syria, was the second Briton executed by
The taxi driver, from Salford, was kidnapped by IS just after Christmas in 2013 when he entered Syria from Turkey with Muslim friends to take supplies to children.
Henning was held for ten months, before video emerged of his execution last October.
In the video the the father-of-two said: "I'm Alan Henning. Because of our parliament's decision to attack the Islamic State I, as a member of the British public, will now pay the price for that decision."
The masked jihadist, thought to be Emwazi, then said: "The blood of David Haines is on your hands, Cameron. Alan Henning will also be slaughtered but his blood is on the hands of the British parliament".
Henning's wife Barbara had made a series of emotional pleas for her husband's life to be spared. She had said: "I ask Islamic State: Please release him. We need him back home. Thank you."
His nephew, Stuart Henning, tweeted on Friday that he had "mixed feelings" as he wanted Emwazi to suffer "the way Alan and his friends did".
His brother Reg Henning told ITV: "Hopefully this is the end of it. I am glad he is dead.
"I would have preferred him to face justice. I think things will quieten down. If they had arrested him and gone to court, it would have dragged on for months and months."
Henning's daughter, Lucy, later revealed she found out about her father's death on Instagram.
The 18-year-old said she had hoped the terror group would release her father and that she was still coming to terms with the brutal nature of the execution.
The video depicting Henning's death ended with Emwzi threatening an American hostage in retaliation for the US bombardment of IS.
US special forces soldier turned aid worker Peter Kassig was beheaded in November 2014. The Telegraph reported claims that the 26-year-old may have been shot first.
David Cameron said Kassig was a "selfless humanitarian worker who had gone to the region to help care for those fleeing the Syrian conflict" and said he wanted Emwazi "to face justice for the appalling acts that have been carried out in Syria".
In a video of the execution the killer spoke in a London accent and said: "To Obama, the dog of Rome. Today we are slaughtering the soldiers of Bashar [al– Assad, the Syrian president] and tomorrow we will be slaughtering your soldiers.
"And with Allah's permission we will break this final and last crusade and the Islamic State will soon, like your puppet David Cameron said, begin to slaughter your people on your streets."
Later, he could be seen with a decapitated head at his feet, which he said to belong to Kassig who is believed to have refused to read out a propaganda statement before his death.
Michael Downey, one of his best friends from Beirut, said: "He was a man of principle and wouldn't give into intimidation from thugs."
Kassig's parents, Paula and Ed Kassig, said they were heartbroken to learn their son had "lost his life as a result of his love for the Syrian people and his desire to ease their suffering. Our heart also goes out to the families of the Syrians who lost their lives."
They added: "We are incredibly proud of our son for living his life according to his humanitarian calling. We will work every day to keep his legacy alive as best we can.
"We remain heartbroken, also, for the families of the other captives who did not make it home safely. The families of James Foley, Steven Sotloff, David Haines, and Alan Henning remain in our daily thoughts and prayers, and we pray for the safe return of all remaining captives held by all sides of the Syrian civil war."
Kenji Goto was beheaded on 30 January 2015 by an IS militant thought to be Jihadi John. Goto was captured by IS in October 2014 after entering Syria in the hopes of rescuing Japanese hostage Haruna Yukawa, who was beheaded a week earlier.
IS had threatened to kill both men unless Japan paid a ransom of $200m – the same amount Prime Minister Shinzo Abe had pledged in non-military aid to countries engaged in the fight the terrorist group.
At the time Abe said Japan "would not give in to terrorism" and that he would expand his support to countries fighting IS.
IS has cited Japanese aid as a reason for the hostage taking.
In a video of Goto's death he is seen kneeling in an orange jumpsuit as a militant speaking with an English accent, thought to be "Jihadi John", addresses Abe, accusing him of a "reckless decision to take part in an unwinnable war".
Abe later called the killing a "heinous act".
Goto's mother Junko Ishido said she was speechless at his death, saying he had gone to Syria out of "kindness and courage".
She told Japanese broadcaster NHK TV: "I was hoping Kenji would come back alive."