U.S. intelligence officials were analyzing Wednesday a video released by Islamic militants showing the beheading of American journalist James Foley, focusing on identifying the surrounding landscape and the British accent of his executioner.
The identification of his killer is said to be of top importance to U.S. and European intelligence officials.
The video -- originally posted by ISIS to YouTube, which later took the video down -- also shows an ISIS militant standing over a second man dressed similarly to Foley in an orange jumpsuit. The video identifies the second man as American journalist Steven Sotloff, and warns that he, too, could be killed. Sotloff was kidnapped near the Syrian-Turkish border in August 2013, and freelanced for Time, the National Interest and MediaLine.
While the Obama administration has not yet officially authenticated the video or confirmed Foley's death, U.S. officials who asked not to be identified told Fox News that the man beheaded in the video is Foley.
A statement by Foley's mother, Diane, posted on the "Find James Foley" Facebook page requested privacy "as we mourn and cherish Jim." A priest arrived at her Rochester, N.H. home on Tuesday.
"We have never been prouder of our son Jim. He gave his life trying to expose the world to the suffering of the Syrian people," the message said. "We implore the kidnappers to spare the lives of the remaining hostages. Like Jim, they are innocents. They have no control over American government policy in Iraq, Syria or anywhere in the world."
The orange jumpsuits worn by both captives in the video are synonymous in Jihadi propaganda with Guantanamo Bay and the first wave of prisoners who were held there at Camp X-Ray.
Fox News has learned that the video, which is being taken seriously by U.S. officials, is being analyzed by a group within the U.S. intelligence community that specializes in media exploitation. The Islamic State militant group, formerly known as the Islamic State of Iraq and Syria, is believed to have other Americans in their custody.
An intelligence source told Fox News that the landscape of the video is being analyzed to determine a likely location. Investigators also are planning to analyze the voices in the tape, including the masked executioner who appears to speak with a British accent, and whether or not the individual is linked to Britons known to have traveled to Syria.
White House National Security Council spokeswoman Caitlin Hayden said the administration has seen the video. She said that if it's deemed genuine by the intelligence community, the U.S. would be "appalled by the brutal murder of an innocent American journalist."
President Obama was briefed on the video Tuesday night by Deputy National Security Adviser Ben Rhodes on Air Force One, Deputy Press Secretary Eric Schultz said.
Adam Schiff, D-Calif., who sits on House Intelligence Committee, called the video “appalling.”
"The apparent beheading of photojournalist James Wright Foley adds to the appalling parade of horrors perpetrated by [ISIS]. Seldom is the descriptor 'evil' applied with perfect accuracy as it is with this monstrous group that glories in death,” he said in a statement. “They know no human decency -- murdering journalists, beheading religious minorities refusing to convert, victimizing women and children, and starving entire communities.”
The video prompted British Prime Minister David Cameron to return to London early from his vacation.
“He will meet with the foreign secretary and senior officials from the Home Office, Foreign Office and the agencies to discuss the situation in Iraq and Syria and the threat posed by [ISIS] terrorists," read a statement from the prime minister’s office.
The release of the video comes amid a U.S. airstrike campaign against Islamic State targets in Iraq. ISIS has declared an Islamic state in the territory it controls in Iraq and neighboring Syria, imposing its harsh interpretation of Islamic law.
Foley, 40, a freelance journalist, vanished in Syria in November 2012 while covering the Syrian civil war for GlobalPost. The car he was riding in was stopped by four militants in a contested battle zone that both Sunni rebel fighters and government forces were trying to control. He had not been heard from since.
The publication "mounted an extensive international investigation" for his whereabouts, with the search extending throughout the Middle East, along the Syria-Turkish border, in Lebanon, Jordan and other locations, GlobalPost reported Tuesday.
In 2011, Foley was among a small group of journalists held captive for six weeks by the government in Libya and was released after receiving a one-year suspended sentence on charges of illegally entering the country. In a May 2011 interview about his experience, he recounted watching a fellow journalist being killed in a firefight and said he would regret that day for the rest of his life. At the time, Foley said he would "would love to go back" to Libya to report on the conflict and spoke of his enduring commitment to the profession of journalism.
"Journalism is journalism," Foley said during the AP interview, which was held in GlobalPost's office in Boston. "If I had a choice to do Nashua (New Hampshire) zoning meetings or give up journalism, I'll do it. I love writing and reporting."
The New York-based Committee to Protect Journalists (CPJ) condemned what it called a "barbaric murder. The organization estimated Tuesday that about 20 journalists are missing in Syria, and has not released their nationalities.
In its annual report last November, CPJ concluded that the missing journalists are either being held and threatened with death by extremists, or taken captive by gangs seeking ransom. The group's report described the widespread seizure of journalists as unprecedented and largely unreported by news organizations in the hope that keeping the kidnappings out of public view may help in the captives' release.
Marquette University, Foley's alma mater, said it was "deeply saddened" by the news of Foley's death. The Milwaukee university said he had a heart for social justice and used his talents to tell stories in the hopes they might make a difference.
"We extend our heartfelt prayers and wishes for healing to James' family and friends during this very difficult time," Marquette University said in a statement.
Earlier Tuesday, GlobalPost CEO and co-founder Philip Balboni in a statement asked "for your prayers for Jim and his family." AFP chairman Emmanuel Hoog said the French news agency was "horrified" by the video and called Foley "a brave, independent and impartial journalist."