A look at those killed or held captive by Islamic State
Since August 2014, the Islamic State has released several videos showing gruesome beheadings and threatening the lives of those it is holding hostage.
Islamic State militants have seized control of large parts of Syria and Iraq. A U.S.-led coalition is carrying out airstrikes against the group.
Here's a look at hostages of the Islamic State — also known as ISIL or ISIS — who are being held or have been killed:
KAYLA JEAN MUELLER, DEAD
The Islamic State claimed on Feb. 6 — without providing any video or photographic evidence — that the 26-year-old American aid worker from Prescott, Ariz., was killed during an airstrike by Jordanian jets in Syria. Officials in Washington and Jordan originally said they had not seen any evidence to support the claims.
On Feb. 10, the White House and Mueller's parents confirmed her death, but didn't elaborate how she died.
Mueller's identity had not been previously released by American officials or her family out of fear for her safety. She was the last known remaining American hostage held by the group.
Mueller had been working in Turkey assisting Syrian refugees when she was taken captive in August 2013 by Islamic State militants in the Syrian city of Aleppo while leaving a Spanish Doctors without Borders hospital, her family said.
In a 2013 article in The Daily Courier, her hometown newspaper, the Northern Arizona University graduate said that she was drawn to help with the situation in Syria.
"For as long as I live, I will not let this suffering be normal," she said. "It's important to stop and realize what we have, why we have it and how privileged we are. And from that place, start caring and get a lot done."
JOHN CANTLIE, HELD HOSTAGE
Since September 2014, the British journalist has appeared in several propaganda videos released by the Islamic State.
In one video, Cantlie, 43, said he has been "abandoned" by his government and promised to reveal the "truth" about the militants. Cantlie, who said he has worked for The Sunday Times, The Sun and The Sunday Telegraphin the U.K., spoke directly into the camera, saying, "Now, I know what you're thinking. You're thinking, 'He's only doing this because he's a prisoner. He's got a gun at his head, and he's being forced to do this.' Right?
"Well, it's true. I am a prisoner. That I cannot deny. But seeing as I've been abandoned by my government and my fate now lies in the hands of the Islamic State, I have nothing to lose."
Cantlie, who was kidnapped in Syria in November 2012, said the news media are trying to "drag the public back to the abyss of another war" with the militant group.
Another video featuring Cantlie was released at the end of October 2014, showing him giving a report claiming the militant group has taken control of the contested Syrian city of Kobani. In January, local forces recaptured Kobani from the Islamic State.
In what he called the "last in this series," a new video released Feb. 9 shows Cantlie in Aleppo, Syria, where he shows destruction he says is caused not only by Syrian President Bashar Assad's regime, but also by U.S.-led coalition airstrikes.
LT. MUATH AL-KASEASBEH, KILLED
The Islamic State released a video Feb. 3 showing al-Kaseasbeh, a Jordanian pilot, being burned alive. The gruesome recording came after a week-long drama over a possible prisoner exchange by Jordan to win the pilot's release.
However, the Jordanian government later reported al-Kaseasbeh's death took place Jan. 3, raising questions about the negotiations for the pilot's freedom.
Jordan had agreed to release Sajida al-Rishawi, an Iraqi woman facing death for her role in the 2005 hotel bombings in Amman but first wanted proof the pilot was alive. Al-Rishawi and another al-Qaeda-linked prisoner were executed several hours after the video of al-Kaseasbeh's death surfaced.
Al-Kaseasbeh was captured by the Islamic State in December after his aircraft crashed over Syria. He was the first, and so far only, foreign military pilot to be captured since the U.S.-led coalition began airstrikes on the militants last year.
His brutal death triggered widespread backlash against the militant group throughout Jordan, which has been conducting airstrikes targeting the Islamic State.
KENJI GOTO, KILLED
The Islamic State released a video Jan. 31 showing the beheading of the Japanese journalist and warning the Tokyo government of "carnage wherever your people are found."
The video shows a masked militant clad in black and brandishing a knife while Goto, wearing an orange jumpsuit, kneels in front of him. Speaking in British-accented English, the militant appears to be the same person seen in previous Islamic State videos and dubbed by Western terror analysts as "Jihad John."
Goto, 47, was captured in October 2014 after going into Syrian territory to try to secure the release of another Japanese hostage, Haruna Yukawa.
The well-known freelance journalist was shown in a previous Islamic State video holding a photo that purported to depict Yukawa's body and included a demand of $200 million ransom for Goto's own release.
HARUNA YUKAWA, KILLED
On Jan. 24, the Islamic State released a video claiming Yukawa had been beheaded and issuing new demands. Yukawa, 42, was the founder of a private security firm and was taken captive in August 2014.
PETER KASSIG, KILLED
American Kassig, 26, was a former Butler University student who worked as an aid worker in Lebanon and Syria before being captured by Islamic State fighters in October 2013.
In fall 2012, Kassig founded SERA — Special Emergency Response and Assistance — a group focused on providing Syrian refugees in Lebanon and Syria with medical assistance, supplies, clothing and food.
During his captivity, his family says Kassig converted to Islam and changed his name to Abdul-Rahman, which means "servant of the most merciful."
In a video showing the beheading of Alan Henning on Oct. 3, 2014, the militant group said Kassig would be next if the United States did not end its military operations in the region.
A video surfaced on Nov. 16, 2014, claiming to show Kassig's beheading.
ALAN HENNING, KILLED
A video appearing online on Oct. 3, 2014, showed Henning's decapitation by a member of the Islamic State. Henning was previously threatened by the militant group in a video released Sept. 13 showing the decapitation of another British aid worker, David Haines.
Henning, 47, a former British taxi cab driver, was on an aid convoy in December 2013 when he was captured after crossing into Syria, the BBC reported.
A video recorded before his capture shows Henning describing his volunteer work in the region, CNN reported. "It's all worthwhile when you see what is needed actually gets where it needs to go," Henning says in the video.
On Sept. 20, 2014, Henning's wife, Barbara, pleaded with the Islamic State for his release. "When they hear this message I implore the people of the Islamic State to see it in their hearts to release my husband Alan Henning," she said in a statement released by the U.K.'s Foreign Office.
DAVID HAINES, KILLED
Haines, 44, a father of two who grew up in Perth, Scotland, then settled in Croatia after working for several humanitarian agencies there and in Libya and South Sudan, was abducted in Syria in 2013.
The video showing his beheading threatened British Prime Minister David Cameron. "For being a lapdog, Cameron, you will drag your people into another bloody and unwinnable war," the video warned.
Haines' brother, Mike, released a statement mourning his family's loss.
"David was most alive and enthusiastic in his humanitarian roles. His joy and anticipation for the work he went to do in Syria is for myself and family the most important element of this whole sad affair," Mike Haines said.
The Islamic State video concluded with a threat against Henning's life.
STEVEN SOTLOFF, KILLED
On Sept. 2, 2014, the group released a video showing the beheading of American journalist Sotloff, days after his mother pleaded for the Islamic State to release him.
In the video, Sotloff, who disappeared Aug. 4, 2013, after crossing from Turkey into Syria, said he was "paying the price" with his life for U.S. intervention in Iraq.
"You've spent billions of U.S. taxpayers' dollars, and we've lost thousands of our troops in our previous fighting against the Islamic State," Sotloff, 31, said. "So where is the people's interest in reigniting this war?"
A hooded man dressed in black blamed President Obama before beheading Sotloff, 31. "I'm back, Obama, and I'm back because of your arrogant foreign policy toward the Islamic State," the man said.
Sotloff had worked in the region as a freelance journalist and was published in Time,Foreign Policy and elsewhere. He was active on social media while he worked in the Middle East.
The video concluded with a warning that Haines would be killed next.
JAMES FOLEY, KILLED
On Aug. 19, 2014, the group released a video showing the decapitation of the 40-year-old American journalistfrom Rochester, N.H. The video said Foley was executed "in Iraq" as a result of President Obama's decision to bomb Islamic State fighters battling Kurdish forces north of Baghdad.
The video concluded by showing Sotloff and telling Obama that his life "depends on your next decision."
Foley, who was abducted at gunpoint near the town of Taftanaz in northern Syria on Nov. 22, 2012, was one of the hostages U.S. ground troops attempted but failed to rescue in Syria in early July 2014, according to the Pentagon.
On Aug. 20, 2014, Obama called the murder "an act of violence that shocks the conscience of the entire world." The president called Foley's parents to say the nation was "heartbroken" at their loss.
"He gave his life trying to expose the world to the suffering of the Syrian people," Foley's mother, Diane, said in a Facebook post on the page Free James Foley. She implored the kidnappers to spare the lives of the rest of the hostages.
Contributing: The Indianapolis Star, The Associated Press
