The head of the investigation of the space shuttle Columbia disaster said yesterday that he does not intend to "cast about" for scapegoats or "cast a chill over NASA" in attempting to pinpoint the cause.

Retired Adm. Harold W. Gehman Jr., chairman of the investigation board, triggered a dispute with NASA Administrator Sean O'Keefe last week by requesting to separate several of NASA's senior shuttle mangers from the probe.

O'Keefe said the transfers would unfairly single out those officials and would "be viewed as prejudging the facts before the investigation is complete."

Yesterday, Gehman told reporters in Houston that his request did not mean that "anybody has done anything wrong." But, he said, some senior shuttle officials who have been assisting the board will inevitably become part of a larger examination of NASA's management style and oversight, and the board cannot be in the position "of having the investigators investigate themselves."

In an apparent effort to allay the concerns at NASA that the board is mounting a "witch hunt," Gehman stressed, "I'm not really interested in casting about NASA -- without any particular focus or without any particular reason . . . [and] casting some big chill over NASA."

O'Keefe said yesterday that agency critics and the news media were jumping the gun in focusing on one possible cause of the accident -- that a debris strike on the left wing at launch caused damage that allowed superheated gases to burn through during reentry to Earth's atmosphere.

O'Keefe and William F. Readdy, NASA's associate administrator for human space flight, also complained that the news media had taken out of context a series of NASA e-mails released last week, including one from an engineer at the Langley Research Center in Virginia who said senior officials were treating information like "the plague."

"When I was down at Langley last week, one of the principals involved in this said: 'I mean this is being characterized as if somehow we were out there waving red flags on this, when nothing could be further from the truth,' " O'Keefe said.