Britain close to identifying James Foley's killer, ambassador saysBy Steve Almasy, CNNUpdated 12:58 PM ET, Tue August 26, 2014Just WatchedAuthorities close to naming ISIS militantreplayMore Videos ...Authorities close to naming ISIS militant 02:05Story highlights Foley family releases letter written by the journalist while in captivity in JuneBritish ambassador says voice identification technology is being used to ID killerA video posted online shows the militant beheading James FoleyThe militant speaks with what experts describe as an English accentBritish officials "are close" to identifying the ISIS militant who beheaded American journalist James Foley, according to Britain's ambassador to the United States, Peter Westmacott.Westmacott told CNN's Candy Crowley on Sunday he couldn't elaborate on the identity of the killer, who is seen decapitating Foley in a video posted last week on YouTube."We're putting a great deal into the search," he said, referring to the use of sophisticated technology to analyze the man's voice. In the video, Foley, 40, is seen kneeling next to a man dressed in black, who speaks with what experts say is a distinctly English accent. Linguists said that based on his voice, the man sounds to be younger than 30. He also appears to have been educated in England from a young age and to be from southern England or London.Just WatchedJames Foley 'smuggled' letters to familyreplayMore Videos ...James Foley 'smuggled' letters to family 01:35PLAY VIDEOJust WatchedVideo holds clues to Foley's killerreplayMore Videos ...Video holds clues to Foley's killer 01:54PLAY VIDEOJust WatchedFoley's family received chilling e-mailsreplayMore Videos ...Foley's family received chilling e-mails 02:38PLAY VIDEOJust WatchedFoley's parents 'underestimated' ISISreplayMore Videos ...Foley's parents 'underestimated' ISIS 01:52PLAY VIDEOJust WatchedCEO: European govts paid 4M for hostagesreplayMore Videos ...CEO: European govts paid 4M for hostages 00:36PLAY VIDEOVoice, words may provide clues about Foley's killerThe video shows another U.S. journalist, identified as Steven Sotloff, being held by ISIS. The militant warned that Sotloff's fate depends on what President Barack Obama does next in Iraq.A day after the video was posted, Obama vowed the United States will be "relentless" in striking back against ISIS.Airstrikes continued to hit ISIS targets near Irbil and the Mosul Dam on Sunday, U.S. Central Command said in a news release. The majority of the strikes have been in support of Iraqi forces near the dam, which briefly fell under ISIS control.Mourners pack Foley's hometown churchMeanwhile Sunday, hundreds of mourners crammed into Foley's hometown church in New Hampshire to attend his memorial Mass."This moment in our lives is international in scope; crossing all boundaries, yet very personal," Bishop Peter A. Libasci said. "[We are] bound together by a deep sense of human compassion and heartfelt remorse." Foley's parents, who received a standing ovation, asked for privacy and thanked mourners for their support. Foley disappeared on November 22, 2012, in northwest Syria, near the border with Turkey. He was reportedly forced into a vehicle by gunmen; he was not heard from again. At the time of his disappearance, he was working as a freelancer for the U.S.-based online news outlet GlobalPost.His family released a letter Sunday said to be written in June by Foley. Because his letters were confiscated in captivity, Foley's family said he asked another hostage set to be released to commit the letter to memory. Just WatchedWho is James Foley's executioner?replayMore Videos ...Who is James Foley's executioner? 00:10PLAY VIDEOJust WatchedThe search for James Foley's killerreplayMore Videos ...The search for James Foley's killer 01:44PLAY VIDEOJust WatchedFreed hostage reflects on FoleyreplayMore Videos ...Freed hostage reflects on Foley 06:22PLAY VIDEOJust WatchedObama: America does not forget replayMore Videos ...Obama: America does not forget 03:17PLAY VIDEOIn the letter, Foley reflects on favorite family memories -- a trip to the mall with his father, a bike ride with his mom -- and gives details of his time in captivity. Comfort from others being held"Eighteen of us have been held together in one cell, which has helped me. We have had each other to have endless long conversations about movies, trivia, sports," Foley wrote, describing makeshift games of checkers, chess and Risk. "The games and teaching each other have helped the time pass. They have been a huge help."He had specific messages of love for his brothers and sister, and to his grandmother he told her, "please take your medicine, take walks and keep dancing."By the time he wrote the letter, he had already been held captive for a year and half, and seemed to waver between remaining hopeful for his release, while also resigned to his fate. While addressing his brothers and sister, he gives specific wishes on who his money should go to and thanks them for "happy childhood memories." But he closes the letter by addressing his "Grammy." "Stay strong," he told her, "because I am going to need your help to reclaim my life."The following month, over the July 4 weekend, U.S. special operations units were sent into Syria to rescue Foley and other hostages held by Islamist militants, a U.S. official told CNN. Several dozen of the most elite U.S. commandos from Delta Force and Navy SEAL Team 6 flew in on helicopters but couldn't find the hostages, including Foley.His captors recently sent an e-mail to his family threatening his death -- a message Philip Balboni, the CEO of GlobalPost, described as "vitriolic and filled with rage against the United States."Foley's captors demanded 100 million euros ($132.5 million) in exchange for his release, Balboni told CNN last week.READ: Brother: 'More ... could have been done' to save James FoleyREAD: Former CIA chief: Matter of time before ISIS tries to attack WestREAD: Opinion: Should we call ISIS 'evil'?ISISISIS governor killed in airstrikes The latest ISIS-appointed governor of Mosul was killed in coalition airstrikes on Christmas Day, according to Iraqi police. Author's journey inside ISISAuthor Juergen Todenhoefer says ISIS are "more dangerous than people realize."The Pentagon has a new name for ISISThere's yet another new name for ISIS among those fighting against the terror group. Daesh. FBI warns military of ISIS threatThe FBI warns U.S military that ISIS are looking for individuals who may be interested in carrying out attacks on home soil.Iraqi army's 'ghost' soldiersIraq's Prime Minister says there is evidence of 50,000 soldiers being paid while inactive.Pentagon insider may lead war on ISISPentagon insider Ashton Carter is expected to be President Barack Obama's nominee for Defense Secretary.U.S. seeks strategy reviewWolf Blitzer talks to Rep. Ed Royce about the White House's new ISIS strategy that involves removing Bashar al-Assad.Child fighter tormented by ISIS Just two weeks ago, Yasir was regularly strapped into an explosive vest and handed guns and a radio to stand guard at an ISIS base in Syria.Jihadi Janes try to join ISISHow did three U.S. teenagers become radicalized? CNN's Pamela Brown reports.Why is ISIS so attractive to recruits?Reza Aslan examines the appeal of ISIS and why the group is able to successfully attract so many recruits.This is how ISIS indoctrinates kids CNN's Nick Paton Walsh takes a look at how ISIS is using media to desensitize children. 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