The murder of ISIS hostage Peter Kassig leaves the terrorist group with just one remaining U.S. hostage, a 26-year-old female aid worker.
Little is known about the unnamed woman, other than that she was captured in Syria last year, and that ISIS has demanded $6million for her release. As part of the deal the group also demanded the release of imprisoned neuroscientist Aafia Siddiqui.
Siddiqui, an MIT-trained neuroscientist, was convicted in 2010 of trying to kill U.S. officials. Authorities believe she may have also been planning the construction of dirty bombs to be used in terrorist attacks.
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Last seen: Peter Kassig - who changed his name to Abdul-Rahman after converting to Islam - was paraded at the end of a graphic video (pictured) last month showing the murder of Brit Alan Henning
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Murdered: President Barack Obama on Sunday paid tribute to American aid worker Mr Kassig (pictured) as an ISIS video purporting to show a militant standing above his severed head was confirmed as genuine
The female aid worker was snatched while helping people displaced by the Syrian war along with other aid workers in August 2013. The other workers are thought to have been released.
It is not known exactly how many Westerners are still held in Syria, but the woman is not thought to be the only one. In September it was reported they could have as many as 24 who were either journalists or aid workers.
Freelance journalist Austin Tice was abducted in Syria more than two years ago. There has been claims that Mr Tice was held by the Syrian government, but this has never been verified, and exactly who is holding him remains unclear. British photojournalist John Cantile is also still being held after being captured in Syria last year and has regularly appeared in ISIS propaganda videos.
The U.S. female hostage is thought to have been particularly motivated to help orphans and other children separated from their families during the war.
Her family has requested her name not be released, as U.S. officials fear further attention could endanger the woman's life.
Exactly what will happen to her remains unclear. She did not appear at the end of a video, released Sunday, showing the aftermath of Mr Kassig's death, which breaks the terrorist group's pattern of introducing its next victim.
ISIS has killed Muslim women, as well as children, but has never murdered a female Western hostage on camera.
A former U.S. counterterrorism official told the The Daily Beast that before ISIS decides what to do with the woman, it will carefully consider how the public would react.
'Before they’re doing anything, they want to have a really good feel for how it will play,' the official said.
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Unsettling: The video also shows the mass murder of Syrian military personnel by beheading led by Jihadi John at a desert location. Unlike the murder of Western hostages, the killing of the Syrians is shown in full
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Confirmation: The White House confirmed Mr Kassig's beheading following an intense review of an ISIS video purporting to show a militant (pictured) standing above his severed head
The website goes on to say that the fact ISIS request ransoms, yet set them too high for most people to pay, suggest the group has no intention of freeing prisoners. Their hostages are simply props used to recruit new members in their global propaganda campaign, it is said.
The Obama administration refuses to pay ransoms and has told families of Americans held in Syria that they could be prosecuted if they paid for their loved ones’ release.
The video showing Mr Kassig’s death had been expected since he was shown on camera in October, at the end of footage showing the murder of British aid worker Alan Henning
The video differs to those earlier released by the group, and may signal a change in their direction and strategy. At 16 minutes, it is considerably longer than the usual two-three minute clips, and it is more brutal.
In the video a gang of ISIS fighters behead 18 hostages. The clip features slow-motion effects and ominous music. The terrorists celebrate the deaths, and there is a call-to-arms.
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Bloodthirsty: The video shows in full graphic detail how the militants saw the heads off their victims
Mr Kassig, who is already dead, appears near the end of the video and is not seen speaking. His executioner says, he had 'little to say'. Other hostages read out statements denouncing the U.S. airstrikes.
In previous films showing victims including James Foley and David Haines, captives kneeled in the sand and spoke out in favor of the so-called Islamic State before being killed.
Several current and former U.S. officials speculated to the Daily Beast that Mr Kassig, who had converted to Islam and adopted the name Abdul Rahman, might have refusing to read pre-written statements: 'I suspect that Pete knew this was coming and that he refused to talk.'
Mr Kassig’s parents, Ed and Paula Kassig of Indiana, had spoken out at length in their efforts to free their son. His conversion to Islam, was a pillar of their arguments for his release.
They said their son was 'fed by a strong desire to use his life to save the lives of others' and that he 'was drawn to the camps that are filled with displaced families and to understaffed hospitals inside Syria'.
PETER KASSIG'S FINAL LETTER
Peter Kassig's apparent murder comes five months after he penned a final letter to his parents, saying he was 'scared to die'.
In the letter, which the Kassigs received on June 2, he wrote: 'I am obviously pretty scared to die but the hardest part is not knowing, wondering, hoping, and wondering if I should even hope at all
'If I do die, I figure that at least you and I can seek refuge and comfort in knowing that I went out as a result of trying to alleviate suffering and helping those in need.'
The hostage, who converted to Islam while imprisoned, told his parents that he prayed every day and was not angry about his situation 'in terms of my faith'.
The letter ended with the words: 'I love you.'
They said: 'We know he found his home amongst the Syrian people, and he hurt when they were hurting.'
Mr Kassig's parents said they hoped their son would be remembered for his 'important work' and his love for others.
'We prefer our son is written about and remembered for his important work and the love he shared with friends and family, not in the manner the hostage takers would use to manipulate Americans and further their cause,' the said.
'The family respectfully asks that the news media avoid playing into the hostage takers’ hands and refrain from publishing or broadcasting photographs or video distributed by the hostage takers.'
The couple also added that they were waiting for the U.S. government to verify the authenticity of the ISIS video - which has since happened
President Barack Obama on Sunday paid tribute to Mr Kassig while attacking ISIS.
Speaking as he flew back to Washington from Hawaii, he said the 26-year-old veteran was 'taken from us in an act of pure evil by a terrorist group that the world rightly associates with inhumanity'.
He said the Islamic State, which now controls a third of Iraq and Syria, 'revels in the slaughter of innocents, including Muslims, and is bent only on sowing death and destruction.'
And he described Mr Kassig as a 'humanitarian who worked to save the lives of Syrians injured and dispossessed', adding: 'We cannot begin to imagine [his family's] anguish at this painful time.'
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Family photo: Mr and Mrs Kassig are seen with their son - who changed his name to Abdul-Rahman
Obama's statement came just minutes after the White House announced that the 16-minute long ISIS propaganda video was real.
It also followed an emotional statement from Mr Kassig's family about he fate of their 'treasured' son.
They are yet to release a statement following the confirmation of his death.
Speaking in the now-familiar London accent of ISIS executioner-cum-spokesman Jihadi John, a masked jihadist warns in the murder video: 'To Obama, the dog of Rome. Today we are slaughtering the soldiers of Bashar 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 in your streets.’
Mr Kassig was captured in Syria in October last year while providing medical training and humanitarian aid to victims of the country's conflict.
Peter Kassig's parents make plea to ISIS for son's return
Previous beheading videos showed a desert landscape but in this latest release appears to be in front of a town with fields in the distance. Mr Kassig's apparent murder is not shown.
At the end of the video, which intersperses various executions with file footage of U.S. forces in Iraq and later clips of Islamic State battles, a bloodied, decapitated head is shown at the feet of a militant wearing khaki boots.
The masked militant may be Jihadi John, the man believed be from Britain who wielded the knife in four previous murders of Western hostages.
His voice sounds similar to the voice of the masked militant who has featured in previous videos. and he has what sounds like a London accent despite his voice being distorted.
However, the news of Mr Kassig's death broke hours after Jihadi John was reportedly injured in U.S. airstrikes on Saturday night.
In the video, the militant says: 'This is Peter Edward Kassig, a U.S. citizen of your country. Peter, who fought against the Muslims in Iraq while serving as a soldier under the American army, doesn't have much to say. His previous cell mates have already spoken on his behalf.
'But we say to you Obama ... you claim to have withdrawn from Iraq four years ago. We said to you then that you are liars, that you have not withdrawn and that if you had withdrawn that you would return, even if after some time.
'You would return. Here you are. You have not withdrawn. Rather, you hid some of your forces behind your proxies and withdrawn the rest. Your forces will return, greater in number than they were before. You will return and your proxies will not benefit you.
ISLAMIC STATE'S WESTERN VICTIMS
James Foley - this 40-year-old American freelance photojournalist was documenting the Syrian civil war when he was snatched in November 2012 in the country's north west. His murder was shown in a video released in August.
Steven Sotloff - an Israeli-American journalist working for both TIME and The Jerusalem Post who was kidnapped in Aleppo, Syria, in 2013. The 31-year-old's apparent beheading was shown in a video released on September 2.
David Haines - the 44-year-old British humanitarian aid worker was taken hostage while working at a refugee camp in Idlib, Syria, near the Turkish border. His abduction only became public when he appeared in the Sotloff execution video. He was apparently killed on camera in a video released on September 13.
Alan Henning - this volunteer aide worker from Britain, 47, had been working with Islamic charities to deliver food and water to people affected by Syria's civil war. He was abducted in the city of Al-Dana when that area fell under the control of Islamic State fighters in December 2013. A video showing his apparent murder was released on October 3.
Peter Kassig - the 26-year-old aid worker from America was captured in October last year in Syria while providing medical training and humanitarian aid to victims of the country's conflict. A video showing his murder was released on Sunday.
'And we also remind you of the haunting words that our Sheikh Abu Musab al-Zarqawi told you. The spark has been lit here in Iraq and its heat will continue to intensify by Allah's permission until it burns the crusader army in Dabiq.
'And here we are, burying the first crusader in Dabiq. Eagerly awaiting for the remainder of your armies to arrive.'
A dateline on the video says it has been shot in Dabiq, which is the location where Islamic State militants believe a decisive final battle will be fought with Western forces.
Footage also shows the militant leading the mass execution of Syrian military personnel by jihadis at a desert location.
Unlike the apparent murders of Western hostages, in which the camera cuts away at the moment their throats are cut, these killings are shown in full.
Mr Kassig had formed the aid organisation Special Emergency Response and Assistance, or SERA, in Turkey to provide aid and assistance to Syrian refugees.
He began delivering food and medical supplies to Syrian refugee camps in 2012 and was also a trained medical assistant who provided trauma care to injured Syrian civilians and helped train 150 civilians in providing medical aid.
Mr and Mrs Kassig said they had been doing all they could to free their son but were silent about his plight for a year at the instructions of the ISIS militants. Mr Kassig told U.S. show CBS This Morning: 'They demand. They simply demand.'
ISIS has declared an Islamic caliphate in the areas under its control in Syria and Iraq, which it governs according to a harsh version of Shariah law.
The U.S. began launching air strikes in Iraq and Syria earlier this year in a bid to halt the group's rapid advance and eventually degrade and destroy it.
David Cameron outlines plans to 'confront' extremism
TIMELINE OF BRUTAL ISLAMIC STATE KILLINGS
By Neil Lancefield, Press Association
The murder of US aid worker Peter Kassig was the fifth such killing to be filmed and released by the Islamic State (IS). Here is a timeline of events, starting with the days leading up to the death of the first hostage, US journalist James Foley.
Summer 2014 - A rescue mission fails to free Mr Foley from a secret location where he is being held by IS. The American freelance journalist, 40, was captured two years earlier.
August 13: Mr Foley's family receive a message that he will be murdered.
August 19: al-Furqan Media, which is controlled by the terror group, releases a video appearing to show Mr Foley's killing. His death apparently happened at some time in the previous week. Social media bosses are forced to act swiftly in banning both the video and still images of the beheading, while concerns mount for fellow reporter and captive Steven Sotloff, who is seen pleading for the US to stop air strikes in Iraq at the end of the video.
August 20: David Cameron cuts short a family holiday in Cornwall to hold meetings in Downing Street over the 'shocking and depraved' murder. Meanwhile, US President Barack Obama remains defiant over his country's war on terror. He says: 'We will be vigilant and we will be relentless.'
August 21: The killer is reported to be a British man who goes under the moniker 'Jihadi John'.
September 2: Mr Cameron condemns the 'disgusting and despicable' video apparently showing Mr Sotloff wearing an orange jumpsuit and being beheaded by IS militants. The alleged killer speaks with a British accent, prompting suggestions he is the man who murdered Mr Foley. It emerges that a British hostage, now known to be aid worker David Haines, is also under threat.
September 4: At the start of a Nato summit in Wales, leaders of the Western alliance show a united front in response to terror threats. Mr Cameron and Mr Obama insist they will not weaken in the face of threats from IS terrorists. The Prime Minister refuses to rule out joining the US in air strikes on IS. He says Britain must 'use everything we have in our armoury' to squash the terrorists out of existence.
September 5: Foreign Secretary Philip Hammond joins Mr Cameron in saying the Government will not hold back on launching air strikes, and says threats on Mr Haines's life by his captors will not deter the UK from taking action. The Nato summit ends with a pledge to 'degrade and defeat' IS militants.
September 9: Defence Secretary Michael Fallon confirms Britain will supply £1.6 million of machine guns and ammunition to Kurdish forces fighting IS militants in northern Iraq as part of a burgeoning international effort to drive back the jihadists.
September 10: Mr Obama authorises air strikes inside Syria for the first time as well as an expansion of strikes in Iraq.
September 13: A video showing the murder of British aid worker Mr Haines is released. The video, which involves the 44-year-old saying Mr Cameron and former PM Tony Blair should be held responsible for his death, is widely condemned. It comes hours after Mr Haines's family issue a plea to his captors to contact them. The clip also includes a threat to kill a second British hostage.
September 14: Mr Cameron calls an emergency meeting of its Cobra committee in the wake of the murder. The next British hostage, 47-year-old minicab driver Alan Henning, is named as the man shown in the video.
September 19: Islamic militants release a propaganda video featuring a British hostage believed to be journalist John Cantlie.
September 23: Islamic extremists release a new propaganda video appearing to feature Mr Cantlie. The clip is the second showing the journalist to be circulated by IS militants in less than a week. It comes as the US - backed by Arab allies - carries out its first wave of air strikes on IS militants in Syria.
September 24: Britain appears ready to ramp up its military involvement in the struggle against IS, as Mr Cameron addresses the United Nations in New York.
September 25: FBI director James Comey is reported to have confirmed that the identity of Jihadi John has been uncovered. However, he refused to give the individual's name publicly.
September 26: MPs vote by 524 to 43 to endorse attacks on the militants in Iraq in support of the United States-led coalition. The vote clears the way for RAF warplanes stationed in Cyprus to begin combat operations as soon as suitable targets are identified.
September 27: RAF Tornado GR4 fighter bombers carry out their first sortie over Iraq since Parliament gave the green light for air strikes without finding any targets to attack.
October 3: A video showing the brutal murder of Mr Henning, 47, by IS militants is posted on the internet. Mr Cameron vows to 'hunt down' the 'repulsive' terrorists responsible for the beheading.
October 7: Former Guantanamo Bay detainee Moazzam Begg claims he offered to help the Government secure the release of Mr Henning but was rebuffed. Mr Begg says he believed he knew those who held the murdered aid worker and had helped secure the release of hostages from extremists in Syria in the past.
October 13: Mr Cantlie's sister urges IS to 'restart dialogue' with his family.
November 16: IS releases a video showing the beheading of American hostage Peter Kassig. The IS militant in the footage speaks with a London accent and appears to be Jihadi John. Mr Kassig was captured in Syria in October 2013 while providing medical training and humanitarian aid to victims of the country's conflict.
Read more: http://www.dailymail.co.uk/news/article-2837552/ISIS-s-U-S-hostage-26-year-old-woman-Aid-worker-travelled-Middle-East-join-orphaned-Syrian-children-kidnapped-year-ago.html#ixzz3JLaCy7P1
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