John Cantlie, who appeared in a series of documentary-style propaganda videos since being captured by Islamic State in late 2012, has told his family to give up hopes of seeing him again in the flesh, Telegraph reported Friday.In an article for ISIS's online propaganda magazine, Cantlie told his family to "let him go and get on with their lives." He thanked them for their efforts to bring about his release and urged them to put an end to their public campaign of doing so, the Telegraph said. He also criticized the British government's refusal to pay a ransom for his release.It remains unclear whether the content of the article was genuine or written under pressure of imprisonment. There is also no independent confirmation that it was Cantlie who, indeed, penned the piece.His fate remains unknown since last Monday's release of the latest episode in his ISIS propaganda "video series." In it, Cantlie appears healthy and can be seen standing in civilian clothing by a pile of crumbled buildings, destroyed by the "Assad air force" and the American anti-ISIS coalition."Today we're going to find out if all these bombs, all this fighting, has even slowed down the advance of the Islamic State," Cantlie said in a script most likely written by Islamic State.Concerns for Cantlie's life have been raised since the release of this latest video, the "last in the series."