Bill Gertz and Jon Ward report that one of the people who illegally accessed the presidential candidates’ passport records works for a company headed by an adviser to the Barack Obama campaign.

The State Department investigation of improper computer access to passport records of three presidential candidates is focusing on one remaining employee — a contract worker with a company headed by an adviser to the presidential campaign of Sen. Barack Obama.

The probe by State’s inspector general will include polygraph tests for supervisors in the passport section to find out whether the three contract employees who accessed the records had a political motive or were part of a political operation to obtain personal data on Mr. Obama, Sen. John McCain or Sen. Hillary Rodham Clinton.

Two of the three contract employees had been fired before The Washington Times first reported Thursday on security breaches involving Mr. Obama’s passport records. The furor expanded yesterday to incidents involving the passport records of Mr. McCain and Mrs. Clinton.

The third employee, who has not been fired, worked for The Analysis Corporation (TAC), which is headed by John O. Brennan, a former CIA agent who is an adviser to Mr. Obama’s presidential campaign on intelligence and foreign policy.

The TAC employee is the only individual to have accessed both Mr. Obama’s and Mr. McCain’s passport information without proper authorization, a State Department spokesman said. That employee, who was not named, triggered an electronic alarm system, officials familiar with the probe said.