British 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 could n'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 . Voice , words may provide clues about Foley 's killer . The 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 church . Meanwhile 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 . In 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 could n'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 .
Foley family releases letter written by the journalist while in captivity in June . British ambassador says voice identification technology is being used to ID killer . A video posted online shows the militant beheading James Foley . The militant speaks with what experts describe as an English accent .