The missing person in the complating political controversy over the Carter administration's plan to remove a successful Republican prosecutor in Philadelphia surfaced yesterday long enough to disclaim any impropriety in the matter.

Rep. Joshua Eilberg (D-Pa.), whose call to the President in early November triggered a Carter order to "expedite" the replacement of David W. Marston, the U.S. attorney for eastern Pennsylvania, said through an aide that he had made the call only as "part of an ongoing effort to get action on the appointment of a Democrat as the U.S. attorney in Philadelphia."

Marston, whose office has successfully prosecuted some of Pennsylvania's most powerful Democratic politicals, is reported be investigating Eilberg as part of an inquiry into financial irregularities in a Philadephia [WORD ILLEGIBLE] project.

Eilberg, who had refused to communist on the matter until yesterday, said, "I have never been notified by anyone that I am the target of any grand jury investigation."

He said he had asked the President in the Nov. 4 and to expedite the change in U.S. attorneys "because I felt that Mr. Marston was using the U.S. attorney's office as a platform from which to run for higher office."

Marston, 5, has said he was told by Associate Attorney General Michael J. Egan in mid-November that he had to be replaced because of "pressure from on high."

Egan then related to him the gist of the Eilberg call to Carter and Carter's subsequent call to Attorney General Griffin B. Bell concerning Marston's removal, Marston said.

During that same visit to Washington in November, Marston told Russell T. Baker Jr., a deputy assistant attorney general in the Criminal Division, that Eilberg's name had come up in an investigation, The Washington Post has learned.

But it appears that, as Bell has insisted, he was never informed of Eilberg's possible involvement. Benjamin R. Civiletti, Baker's boss as head of the Criminal Division, said in a phone interview from Seoul, South Korea yesterday that he recalled bearing "something vague about a past or preliminary investigation" of Eilberg last June during some hearings on a grand jury "reform" bill that Eilberg had sponsored.

Civiletti, who is in Seoul for the questioning of indicted Korean agent Tongsun Park, [WORD ILLEGIBLE] it is his practice to inform Bell [WORD ILLEGIBLE] member of Congress is under "serious" investigation "as a matter of avoiding embarrassment or inopportune meetings."

But he said he told Bell nothing about the mention of Eilberg because he considered it "insignificant and never heard anything else about it." He added that he had not been aware of Eilberg's call to the president or Carter's ensuing call to Bell.

This explanation seems to take some of the sting out of the "obstruction of justice" charges which some Republican leaders have been leveling at the Carter administration.

But Carter came under increasing criticism yesterday for the stilted explanation of his personal involvement in the case, wich he expressed at his news conference Thursday, and for the apparent contradiction between his action and his campaign promise to take politics out of such appointments.

When first asked about the case at his news conference Thursday, Carter had said he was not familiar with it until the recent heavy publicity, which has resulted in a flood of calls and telegrams of protest from the Philadelphia area to the White House.

"I have not interfered in it at all," he said.

When asked directly by another questioner about being called by a congressman, however, he acknowledged the exchange with Eilberg.

A Justice Department spokesman yesterday said Carter and Bell apparently had discussed the case twice, once before the call from Eilberg when Pennsylvania Democratic House members were meeting to pick a successor to Marston.

David Cohen, president of Common Cause, a public advocacy group sent a telegram to Carter yesterday saying the decision to remove Marston was "an affront to the concept of fair and impartial administrator of justice," and that the circumstance surrounding the decision "make a mockery" of his campaign pledge.

He urged Carter to reverse the decision.

Bill Brock, chairman of the Republican National Committee, issued a statement saying that the incident had "overtones of a political coverup" because of the reports that Marston was conducting investigations of Pennsylvania Democrats.