WASHINGTON - The investigation into who leaked the identity of an undercover CIA officer is shining a spotlight on a 30-year Justice Department prosecutor more accustomed to staying out of the public eye on even the biggest cases.
John Dion, a 57-year-old Notre Dame graduate, is chief of the agency's counterespionage section, a group of a dozen career public servants who specialize in the government's most sensitive national security investigations.
In recent years, these have included FBI spy Robert Hanssen, CIA spy Aldrich Ames and accused al-Qaida conspirator Zacarias Moussaoui.
As high-profile as those cases were, none included the political overtones of the CIA leak probe, which is focused on the White House and has drawn Democratic calls for appointment of a special counsel to remove possible conflicts of interest for Attorney General John Ashcroft.
The investigation concerns who leaked to several reporters the name of Valerie Plame, a CIA undercover officer married to former Ambassador Joseph C. Wilson. The leak followed Wilson's public charges that President Bush was manipulating intelligence to exaggerate the threat posed by Iraq.
Those who have worked with Dion say he will not shy away from advocating charges against any high-level Bush administration official if that's where the investigation leads.
"I have no doubt that John has all the independence necessary to do his job the right way," said Paul McNulty, U.S. attorney for Virginia's eastern district. "He is used to working on cases that get a lot of attention. He is a thoughtful, careful person."
But not, associates say, a man who likes the limelight.
That trait was underscored Wednesday at a Justice Department awards ceremony when Dion was jokingly introduced by Bruce Schwartz, a deputy assistant attorney general who is Dion's immediate superior, as "a man whose name has been torn from today's headlines."
Dion is declining all interview requests and even refuses to release a photograph of himself to news organizations.
He came to the Justice Department in 1973 as part of its honors program, shortly after graduating from George Washington University law school and the University of Notre Dame. He joined what then was called the internal security section in 1980, gradually rising through the ranks until he became acting chief in 1997 and chief in 2002.
Dion has twice received the John Marshall Award for Outstanding Achievement, one of the highest Justice Department awards: first in 1987 for work on the Walker family spy ring case and again in 1997 for espionage prosecutions of FBI agent Earl Pitts and CIA officer Harold Nicholson.
The Walker case involved a former Navy officer, John Walker Jr., and several family members who were convicted of spying for the Soviet Union. Pitts is serving a 27-year sentence for selling secrets to the Soviet Union and Russia; Nicholson was sentenced to 23 years in prison in 1997 for providing Russia with names of CIA officers and other classified documents.
Dion's challenge in the CIA leak was underscored Thursday when four senior Democratic senators wrote in a letter to Bush that Ashcroft's close ties to the White House will raise questions about the outcome of any investigation.
