WASHINGTON - The Justice Department is investigating whether its former White House liaison used political affiliations in deciding whom to hire as entry-level prosecutors in some U.S. attorney offices around the country.

Such consideration would be a violation of federal law.

The inquiry involving Monica Goodling, former counsel and White House liaison for Attorney General Alberto R. Gonzales, raises new concerns that politics might have cast a shadow over the independence of trial prosecutors who enforce U.S. laws.

Justice spokesman Dean Boyd confirmed yesterday that the department's inspector general and Office of Professional Responsibility were investigating Goodling's role in hiring career attorneys - an unusual responsibility for her to have had.

Investigators are trying to determine whether she "may have taken prohibited considerations into account during such review," Boyd said.

Three government officials with knowledge of the investigation said Goodling appeared to have sought information about party affiliation while vetting applicants for assistant U.S. attorneys' jobs. The officials spoke on condition of anonymity because of the investigation.

Goodling's attorney, John Dowd, declined to comment.

Separately, senators subpoenaed Gonzales yesterday, directing him to provide any e-mail related to presidential adviser Karl Rove and the firings of eight federal prosecutors. In Jackson, Miss., Gonzales ended a news conference about the Virginia Tech shootings after he was asked about being subpoenaed.

"I don't want to comment on it without going back and talking to folks within the department," Gonzales said.

Additionally, new documents surfaced yesterday showing that at least four of the eight targeted U.S. attorneys reported being told to stay quiet about their dismissals by Mike Elston, the top aide to Deputy Attorney General Paul McNulty.

Gonzales, with President Bush's backing, has resisted calls for his resignation over the dismissals, which Democrats say appeared to have been politically motivated.

Last month, Goodling quit the Justice Department after refusing to testify to Congress about her role in the firings. The House Judiciary Committee has voted to give her immunity from prosecution for her testimony - an offer the Justice Department is reviewing to make sure it does not interfere with any criminal investigations.

House Judiciary Chairman John Conyers Jr. (D., Mich.) said the new investigation "suggests politics infected the most basic operations" at Justice.

Goodling and Kyle Sampson, Gonzales' former chief of staff, also had authority to hire or fire about 135 politically appointed Justice employees who did not require Senate confirmation.

Asked whether he had ever heard of the department's White House liaison getting involved in the hiring of career prosecutors, Dennis Boyd, executive director of the National Association of Assistant United States Attorneys, said: "No, never." Boyd, who is no relation to the Justice spokesman, declined to comment further.

The investigation of Goodling appears to focus on her role in reviewing applications for trial prosecutors for offices headed by temporary or acting U.S. attorneys who had not been confirmed by the Senate. That responsibility is usually handled by Justice's executive office of U.S. attorneys.

Goodling served in the executive office until she was transferred to become Gonzales' counsel and primary White House contact. The internal Justice inquiry concerns her review of job applicants only after she joined the attorney general's office, the government officials said.

An official's using political affiliation in choosing such applicants clearly would violate traditional Justice Department policy and practice, said Joe diGenova, who was the U.S. attorney in the District of Columbia during the Reagan administration.

"There is no justification for it," diGenova said. "Politics should play no role in the decision-making process of career prosecutors. And if it does, that's clearly improper."

Federal law also bars discrimination against employees or job applicants on the basis of political affiliation.

Meanwhile, the House Judiciary Committee released new statements from three of the dismissed U.S. attorneys contending they received calls from McNulty chief of staff Elston, admonishing them to keep quiet. A fourth former U.S. attorney, Bud Cummins in Little Rock, made a similar accusation in an e-mail released in March.

"I believe that Elston was offering me a quid pro quo agreement: my silence in exchange for the attorney general's," wrote Paul Charlton, the former U.S. attorney in Arizona, according to statements released by the House panel.

John McKay, the former top prosecutor in Seattle, said he perceived a "threat" from Elston during his call. And Carol Lam, who was U.S. attorney in San Diego, said that "during one phone call, Michael Elston erroneously accused me of 'leaking' my dismissal to the press, and criticized me for talking to other dismissed U.S. attorneys."

Bob Driscoll, Elston's attorney, said, "There certainly was no intention to threaten anybody."

Another fired U.S. attorney, Daniel Bogden of Nevada, said he was told his dismissal was necessary to let a Republican lawyer get experience to qualify for a federal judgeship, Bloomberg News reported.

In written answers to supplement his House Judiciary testimony, Bogden said acting Associate Attorney General William Mercer had given him that rationale for his firing.