Steven Sotloff's fixer in Syria tried to get him released last year

The fixer who was kidnapped alongside American Steven Sotloff in Syria last year remembered the slain journalist as a "good" man on Wednesday, saying he did everything possible to persuade their captors to release Sotloff.

Youssef — whose surname is being withheld to protect his family from possible consequences for speaking out about Sotloff's death — was held in the same building as Sotloff for 15 days before being released.

Sotloff was a freelance journalist who travelled the Middle East writing for Time magazine and Foreign Policy magazine, among others.

The pair were captured while travelling together from Turkey to Aleppo, Syria, in August 2013 by a group of men that Youssef said he believes were members of ISIS, the jihadist group that has taken large swaths of territory in Syria and Iraq and also claimed responsibility for the beheading of Sotloff. The grisly murder was taped and posted online on Tuesday.

In an interview with CBC's As It Happens from his home in Turkey on Wednesday, Youssef recalled the pair were ambushed by 15-20 militants who confiscated their car and took them to a building in Aleppo. Youssef said when they arrived at the makeshift prison, the pair were separated. It was the last time he saw Sotloff alive.

"I didn't hear any voice from Steven after that time ... Never again," he told As It Happens host Carol Off.

Youssef said that he was eventually released by the militants after they discovered his affiliation with another Syrian rebel group, a loose ally of ISIS in the ongoing fight against Syrian government forces.

After his release, he said, he posted news of the kidnapping to social media networks and contacted others in the small community of fixers working on the Turkey-Syria border to alert them to Sotloff's captivity.

"I did my best," he recalled emotionally. "To his family, I would say, 'I'm sorry.'"

Sotloff a 'gentle soul'

Sotloff's family said on Wednesday he was no hero and no war junkie but "a mere man who tried to find good concealed in a world of darkness."

Barak Barfi, a friend of Sotloff who is serving as a family spokesman, read a statement from the family remembering the slain journalist as a "gentle soul" — a fan of the NFL's Miami Dolphins who was fond of junk food, enjoyed the TV series South Park and liked to talk to his father about golf.

The statement said the 31-year-old Sotloff was "torn between two worlds" but "the Arab world pulled him."

"He was no war junkie. He did not want to be a modern-day Lawrence of Arabia. He merely wanted to give voice to those who had none," Barfi said outside the family's one-storey home in a leafy Miami suburb. "He ultimately sacrificed his life to bring their story to the world."

​U.S. President Barack Obama vowed to destroy the jihadist group on Wednesday during a press conference shortly after the White House confirmed the authenticity of the beheading video.

Another American journalist, James Foley, was shown being beheaded in a video released on Aug. 19. Both videos claim the murders were in retaliation for ongoing U.S. airstrikes in Iraq.

"Steve was no hero," the family statement said. "Like all of us, he was a mere man who tried to find good concealed in a world of darkness. And if it did not exist, he tried to create it. He always sought to help those less privileged than himself, offering career services and precious contacts to newcomers in the region."

'Degrade and destroy'

Obama said the U.S. will build a coalition to destroy the Islamic State.

Obama still did not give a timeline for deciding on a strategy to go after the extremist group's operations in Syria. "It'll take time to roll them back," the president said at a news conference during a visit to Europe.

Obama vowed the U.S. would not forget the "terrible crime against these two fine young men."

"Our reach is long, and justice will be served," Obama said.

Sotloff also held Israeli citizenship, Israel said on Wednesday after apparently withholding the information in a bid to stem the risks to the captive. He was also reported to be the grandson of two Holocaust survivors.

In the Sotloff video, a masked militant warns Obama that the violence will continue as long as U.S. airstrikes against the militant group continue.

Obama responded that he will continue to fight the militant threat and the "barbaric and ultimately empty vision" it represents.

"Our objective is to make sure that [ISIS] is not an ongoing threat to the region," he said. "And we can accomplish that. It's going to take some time and it's going to take some effort."

Vice-President Joe Biden, during an appearance in Maine, said the U.S. would follow the militants.

"When people harm Americans, we don't retreat, we don't forget," Biden said. "They should know we will follow them to the gates of hell until they are brought to justice. Because hell is where they'll reside."

In Washington, Secretary of State John Kerry said that that "barbarity, sadly, isn't new to our world; neither is evil."

Speaking later at a U.S. Diplomacy Center event, he added:

"I can tell you for certain most of the world does not lie awake at night worrying about America's presence. They tell me that they worry what would happen in our absence …. We have to remember engagement and leadership, not retrenchment and isolationism, are the American DNA.

"It is doing the difficult work that makes America's values real in the world which ultimately defines us as a country."

Vanished last year

Sotloff, a 31-year-old Miami-area native, hadn't been seen in more than a year, until he appeared in the video that showed Foley's beheading.

Dressed in an orange jumpsuit against an arid Syrian landscape, Sotloff was threatened in that video with death unless the U.S. stopped airstrikes on the Islamic State.

In the video distributed Tuesday and titled "A Second Message to America," Sotloff appears in a similar jumpsuit before he is apparently beheaded by a fighter with the Islamic State, the extremist group that has conquered wide swaths of territory across Syria and Iraq and declared itself a caliphate.

British Foreign Secretary Philip Hammond told the BBC Wednesday that the masked, British-accented jihadist appears to be the same person shown in the Foley footage.

In the video, the organization threatens to kill another hostage, this one identified as a British citizen.

Last week, Sotloff's mother, Shirley Sotloff, pleaded with his captors for mercy, saying in a video that her son was "an innocent journalist" and "an honourable man" who "has always tried to help the weak."

Obama said the prayers of the American people are with the family of the "devoted and courageous journalist" who deeply loved the Islamic world and whose "life stood in stark contrast to those who murdered him so brutally."

"Whatever these murderers think they will achieve by murdering innocents like Steven, they have already failed," Obama said.

"They failed because, like people around the world, Americans are repulsed by their barbarism. We will not be intimidated. Their horrific act only unite us as a country and stiffen the resolve to take the fight against these terrorists. Those who make the mistake of harming Americans will learn we will not forget."

State Department spokeswoman Jen Psaki said Tuesday that it is believed that "a few" Americans are still being held by the Islamic State. Psaki would not give any specifics, but one is a 26-year-old woman who was kidnapped while doing humanitarian aid work in Syria, according to a family representative who asked that the hostage not be identified out of fear for her safety.