``We are concentrating our efforts on determining from the evidence, including the cockpit voice recorder, whether or not this investigation is to remain under the leadership of the National Transportation Safety Board,'' NTSB chairman Jim Hall told a news conference on Monday.

ABC news reported that during one portion of the tape the pilot left the cockpit and the co-pilot was overheard saying something of a religious nature in Arabic about going into death. A senior law enforcement official said Monday night that he believed that the tape showed that after one of the two pilots left the cockpit, another crew member made the suspicious utterance, believed to have been a prayer, the New York Times said.

The Cable News network reported that Halldiscussed handing over investigative responsibility for the crash in a meeting on Monday with FBI Director Louis Freeh, turning the probe into a criminal investigation.