AUSTIN, Texas, Jan. 24 (AP) -- The man accused of kidnapping and extorting money from atheist leader Madalyn Murray O'Hair and her family agreed to a deal Wednesday that may uncloak the mystery of their disappearance. However, U.S. District Judge Sam Sparks ordered the details of David Roland Waters' plea agreement sealed and cleared the courtroom during a pretrial hearing.

Prosecutors and several reporters objected to Sparks' action, which came at the request of Waters' attorneys.

The judge said his decision was "based on the recent disclosure and publication of sensitive information that could jeopardize the safety of persons both in and out of custody, and based on the recent publication of certain facts that would hinder the investigation."

An attorney for The Associated Press, Jim Hemphill, said he was preparing a motion to unseal a transcript of the proceedings.

The threshold for closing a pretrial hearing is supposed to be "very high, as serious, for example, as national security or the information might put someone's life in immediate danger," Hemphill said.

Waters, 53, faced a five-count indictment alleging that he and others kidnapped O'Hair and her family in a plot that investigators believe ended in their deaths. He faced up to life in prison if convicted. Waters once worked as O'Hair's office manager.

The Austin American-Statesman quoted sources in Wednesday's editions as saying Waters would plead guilty to a lesser charge and lead investigators to O'Hair's body in exchange for a reduced prison term.

Sentencing was set for March 30, according to Sparks' clerk.

Assistant U.S. Attorney Gerald Carruth said only that Waters' trial set for next Monday was canceled and that he anticipated "some closure to this case." Bill Gates, Waters' attorney, would not comment.

O'Hair, son Jon Garth Murray and granddaughter Robin Murray O'Hair disappeared from San Antonio in 1995 along with $500,000 worth of gold coins. Federal investigators believe they were killed and dismembered.

Last August, Gary Paul Karr, 52, a former jailmate of Waters in Illinois, was sentenced to life in prison for extorting more than $600,000 from the O'Hair family. Karr was acquitted of a kidnapping charge. Much of his trial relied on evidence that tied Waters to the alleged crime.

Another suspect, Danny Fry, was found beheaded in 1995 shortly after the family disappeared.

O'Hair reveled in calling herself the most hated woman in America. She was involved in successful court battles in the 1960s to remove prayer and Bible-reading from the nation's public schools. She was 77 when she vanished.