Germany is looking into a claim by Islamic State that one of its followers was responsible for a fatal stabbing in the German city of Hamburg two weeks ago in which a young couple were attacked. A police spokesman in Hamburg said on Sunday local investigators were checking the claim in a statement published by the militant group's Amaq news agency over the weekend, but added that it raised a number of questions. 'What I can say about the current state of the investigation is that we have many questions about this claim of responsibility and therefore we cannot give a definitive evaluation of it,' spokesman Timo Zill told Reuters.