Frank A. DeFilippo, the former press secretary and chief of staff for Maryland Gov. Marvin Mandel, today contradicted two statements made by the governor on the witness stand as prosecutors sought to challenge the governor's truthfulness.

Mandel had testified that he was receiving payments from businessman W. Dale Hess for legal fees owed him, and that he ended the payments because of the adverse publicity he received earlier about his role in a real estate venture. DeFilippo testified, however, that Mandel told him he was ending the payments, called "bribes" by the prosecution because of a law taking effect in 1973 requiring public disclosure of such fees.

DeFilippo also disputed Mandel's testimony concerning the date the governor knew of a partnership agreement between Mandel and hess, a document that later turned out to have been forged and backdated DeFilippo said Mandel told him about it in mid 1975, while Mandel told the jury he did not learn about it until several months later when he was indicted on corruption charges in November, 1975.

DeFilippo was a reluctant witness as he had been at the beginning of the trial - called by U.S. prosecutors to challenge his former boss's testimony into question as the trial enters its final phase.

After 39 days of testimony and 103 witnesses, the prosecution and the defense rested their cases with final rebuttal witnesses. Following a day of preparation, the lawyers on both sides are scheduled to begin summations on Saturday. The jury is expected to get the case sometime late Monday or early Tuesday.

The question of why Mandel ended the payments and when he knew of the partnership documents is important to prosecutors because it speaks to the governor's intent in those transactions. An effort to avoid the disclosure requirement for example, has been interpreted by prosecutors to indicate that Mandel was anxious to hide the payments because they were illegal.

"As I recall," said DeFilippo, now a Baltimore advertising executive, "the governor stated to me that he had decided when the financial disclosure law passed (in 1973) to dicontinue the payment of legal fees from Dale Hess."

"Did he tell you why" asked chief prosecutor Barnet D. Skolnik.

"Because of the financial disclosure law," responded DeFilippo, contradicting the testimony of the man for whom he was said to have served as an "alter ego."

The document raised by prosecutors today was a letter, backdated by six years, stating that codefendant hess owed the governor $15,000 for legal fees incurred in the 1960s, before Mandel was governor. Mandel said he was unaware of it until his indictment, DeFilippo said it was half a year earlier than that.

Mandel is charged with taking $350,000 worth of bribes from Hess, Harry W. Rodgers, William A. Rodgers, Irvin Kovens and Ernest N. Cory Jr., in exchange for his help in getting legislation benefiting the Marlboro Race Track, which the codefendants allegedly owned secretly.

Besides calling DeFilippo to testify, Skolnik presented other witnesses who called into question Mandel's role in the partnership and his promotion of race track legislation that is at the heart of the federal indictment.

Washington Post reporter Edward Walsh was called to verify quotes in a 1975 article he wrote. In the article, State Sen. Roy Staten was quoted as saying "I guess it had been decided that the governor didn't have any objection" to the override in 1972 of a veto of a bill that benefited Marlboro Race Track. "The only conclusion I could reach is that the policy of the administration was then that if you want to override, go ahead," Staten was quoted as saying.

Staten testified earlier that he never made those comments to Walsh. After unsuccessfully seeking to quash the subpoena of him. Walsh said Staten had made the statements.

Lawyers for The Post and trial attorneys had agreed earlier that notes of Walsh's interview with Staten would not be produced at the trial because the paper's lawyers claimed constitutional privilege.

That statement from Staten, calls into question Mandel's claim that he opposed the override.

In its multicount indictment, the federal prosecution team charges Mandel with promoting the override and other 1972 legislative actions to benefit the Marlboro Race Track.

Arnold M. Weiner, attorney for Mandel, called two witnesses to testify against Helen Polinger, former wife of deceased Maryland State Racing commissioner Milton J. Polinger, who testified yesterday that her late husband told her of telephone conversations with Kovens that led to his approval of extra days for the track.

Polinger's former attorney and his former partner testified that the 1976 divorce of the couple was especially bitter and that two days before Helen Polinger volunteered to testify for the prosecution she had had an angry dispute over the custody of their children.

The response, the prosecutors put into evidence a post-divorce photograph of the couple standing next to a horse with their arms around each other.

Skolnik also asked DeFilippo to explain the explanation he gave in 1974 to Washington Post reporters Fred Barbash and Walsh about an $8,000 item Mandel listed in his 1973 income tax return. That item, DeFilippo said at first, represented the share from a dissolution of a stock pool from Mandel's old law firm.

It took more than six months, Skolnik pointed out, before DeFilippo "clarified" the item, saying it was for legal fees owed Mandel. Those fees, according to testimony in the trial, came from Hess as payment from the partnership allegedly contracted to pay back old fees.

The prosecution has contended that the legal fees explanation was devised by Mandel and Hess after the investigation to cover up what the prosecutors consider a bribe. The back-dated letter is one of the reasons that the prosecution says it believes that the legal fees do not exist.

Hess ordered his secretary in 1974, a month after he was notified of the investigation, to type up a letter showing he owed Mandel $15,000 and to back date it to March, 1968.

When Mandel was presented with the letter on the witness stand he claimed he had never seen it before, although it was addressed to him, and that he had only heard of it after his indictment in November, 1975.