US authorities in Iraq have launched an investigation into the killing of the American citizen Nick Berg.
The US has also pledged to catch the Iraqis who killed Berg.
His beheading was taped and shown on an Arabic-language website. The masked men who butchered him claimed they were angered by coalition abuses of Iraqi prisoners.
Late on Wednesday Egyptian experts verified the voice on the tape. According to AFP reports the voice is that of Osama bin Laden's closest associate Abu Musab al-Zarqawi.
The relatives of the killed man complained of lack of enough information concerning the incident. US officials, however, said that Berg had been warned to leave Iraq but refused to do so.
The beheaded man's body was found last Saturday. It was transported to Kuwait, and should be taken to Germany before the Delaware flight.