* Mueller, who was Adolf Eichmann's immediate superior, was held in a U.S. civilian detention camp in late 1945, but was apparently released. It is possible that the CIA recruited Mueller, an expert on communism.

* Mueller killed his wife, three children and himself two days before Hitler committed suicide. However, Mueller's supposed grave in Berlin was opened more than 30 years ago and was found to contain two unknown soldiers.

* Mueller joined Soviet intelligence and was stationed in Czechoslovakia.

* Other Mueller "sightings" were reported in East Germany, Switzerland, Brazil, Argentina, Paraguay, Damascus, Washington — and even New Hampshire.

Mueller was born April 25, 1900, so the possibility that he is still alive is extremely slim.

However, Rabbi Marvin Hier, dean of the Simon Wiesenthal Center, told a news conference Monday, "The U.S. government owes it to history and to the millions who died and were tortured to fill in the gaps and finally tell us all they know about him."

The mysterious case has been pursued for decades by the U.S. Justice Department's Office of Special Investigations, whose director, Eli Rosenbaum, believes that the answer may be found in Soviet archives.

The Wiesenthal Center officially joined the search in 1996, when Hier asked for the "Mueller files" from the CIA, FBI, Justice Department and former Secretary of Defense William Cohen under the Freedom of Information Act.

After a two-year wait, the government released 15 pages with little useful information and the notation that most of the files remain secret to protect national security.

The Wiesenthal Center tried again, and in February 1999 received an additional 128 pages. Included were some index cards with a 1961 memo by an American officer who wrote that Mueller had been held in an internment camp on Dec. 28, 1945, but that the "case was closed" on Jan. 29, 1946.

On Feb. 22, the National Archives announced that the CIA had found another 500 pages of the Mueller files, which are to be made public in about a month.