NASA Administrator Sean O'Keefe has balked at a request from the board investigating the Columbia shuttle disaster to reassign high-level shuttle officials assisting the investigation, saying the move "will be viewed as prejudging the facts" before the probe is completed.

In a Feb. 28 letter NASA released yesterday, O'Keefe bluntly told retired Adm. Harold W. Gehman Jr., chairman of the Columbia Accident Investigation Board, that "I will not submit anybody to . . . treatment" that suggests a NASA official has a conflict of interest with investigators.

"However, since your investigation has matured, it is apparent that our original structure needs to transition as well," O'Keefe wrote. He said NASA would assign advisers to the board who came from outside shuttle program management.

Despite the letter's tone, NASA spokesman Glenn Mahone said O'Keefe did not intend to be "testy," but simply wanted to avoid any appearance of stigmatizing NASA personnel. "It would have a terrible effect throughout the workforce," Mahone said.

O'Keefe was responding to a Feb. 25 letter from Gehman, who noted that "now that the initial recovery and response actions are behind us," the board wanted to "reassign the top-level Space Shuttle Program management personnel" assisting the probe because they were directly involved in the Columbia flight.

"We believe it is in the best interest of these key people, NASA and the effective progress of the investigation if they were to be replaced by other knowledgeable people to manage the response and investigation support."

O'Keefe has several times modified the board's mandate to respond to complaints from Congress that it needed to be more independent, but Gehman's request received a poor reception.

"I am convinced this course of action will be viewed as prejudging the facts before the investigation is complete," O'Keefe wrote. "Despite your assurances that no conclusions have been made arising from the facts of the investigation at this time, simply reassigning personnel will not accomplish your stated goal.

"Moreover," he added, "new personnel could be subjected to the same appearance of conflict in the future, and I will not submit anyone to this treatment."

NASA chief Sean O'Keefe rejects request of investigating board Chairman Harold W. Gehman Jr., but said advisers would be assigned.