WASHINGTON (CNN) -- The Justice Department Tuesday said its prosecutors are assisting the State Department Inspector General in the investigation into the breaching of passport files of the three leading presidential candidates by State Department contractors.
The passport files of Sens. Barack Obama, Hillary Clinton and John McCain were improperly accessed.
The involvement of its lawyers appears to be a shift in the Justice Department's position since Friday, when Attorney General Michael Mukasey said he wouldn't join the investigation until the State Department inspector general requested assistance.
In the event someone walked into the Justice Department "with a box full of evidence," Mukasey said Friday, that could change his stance.
The State Department confirmed last week that contract personnel had accessed Sen. Barack Obama's file on three occasions, and had made unauthorized entry once each into the passport files of Sen. Hillary Clinton and Sen. John McCain. Obama and Clinton are competing to be the Democratic nominee for president. McCain is the likely Republican nominee.
Justice prosecutors met with State Department officials "after the attorney general's remarks on Friday and are coordinating with the Office of Inspector General on its investigative efforts," Justice spokesman Peter Carr said Tuesday. 
Watch more on the passport breach »
He said the department would have no further comment.
The State Department initiated the contact and a follow-up meeting with Justice prosecutors sometime after Mukasey spoke, according to a knowledgeable official who asked not to be identified because of the pending investigation.
The official said the guidance requested by State officials does not constitute what could be described as a "joint investigation" by the two departments. Watch the Secretary of State's comments »
State Department spokesman Sean McCormack said Monday the Justice Department had an "open invitation to be involved in the process" and it would be "up to the Department of Justice as to what sort of involvement they will have."
Several members of Congress have urged the Justice Department to launch a criminal investigation to determine whether charges should be brought.
The latest such call came Tuesday from the chairman of the Senate Judiciary Committee, Sen. Patrick Leahy, D-Vermont, and the panel's ranking Republican, Sen. Arlen Specter of Pennsylvania.
"The Justice Department should not wait to be handed 'a box full of evidence' as you said at your recent briefing, before determining whether federal laws were broken," Leahy and Specter said in a joint letter to Mukasey. "We both strongly believe that our government has a duty to protect the private information of its citizens." E-mail to a friend 
CNN's Elise Labott contributed to this report.
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