A former Maryland school construction official accused former governor Marvin Mandel this week of being present while a $20,000 bribe was offered several years ago, prompting Mandel to brand the accusation "an outrageous lie" and declare: "I'm tired of being the whipping boy for everyone who has a problem."

The allegations against the imprisoned former governor were made by Alford M. (Skip) Carey Jr., who himself went to prison for embezzling money in the mid-1970s from the scandal-ridden state school construction agency to which Mandel had appointed him executive director.

Carey told a state court judge in Annapolis on Monday that Mandel was present during a conversation in which Carey was offered a $20,000 bribe by an associate to the governor to keep under contract a firm favored by Mandel that was not living up to its contract to build portable classrooms for the state.

Speaking by telephone from the federal prison camp at Eglin, Fla., where he is serving a three-year sentence for political corruption, Mandel described himself last night as "a sitting duck" unable to answer accusations made against him.

Using uncharacteristically profane language, Mandel accused Carey of "trying to save his own neck with a total, absolute fabrication."

If Carey's intention was to provide prosecutors with yet another story about the corruption-riddled Mandel administration to avoid a second prison term, he succeeded, for Anne Arundel County Circuit Court Judge F. Mackall Childs placed Carey on probation for his admitted role in a bribery and extortion scheme.

In a four-page affidavit, Carey testified that in Mandel's presence he was offered $20,000 by either W. Dale Hess or Harry W. Rodgers III, two of the men currently serving federal prison terms along with Mandel for their part in an unrelated corruption case, if Carey would allow Globe Industries, a North Carolina firm in which the Hess-rodgers insurance firm had a financial interest, to continue doing business for the state, despite a poor work record.

George A. Nilson, deputy attorney general who represented the state, said today that a series of circumstances, including expiration of the statute of limitations and the difficulty, if not impossibility, of corroborating part of Carey's story, "makes further criminal prosecution unlikely, although that possibility is not totally closed."

Judge Childs said today that he was puzzled that prosecutors had questioned Carey for a year, delaying his sentencing, but then felt they could bring no new charges.

Hess, who is serving his time at Maxwell (Ala.) Federal Prison Camp, told the Sun that "I hardly ever knew what Globe was." Hess denounced Carey as "a liar."

William G. Hundley, Hess' lawyer, said prosecutors had mentioned Carey's tale to him last year, at a time Hess was cooperating with prosecutors in Harford County on another public corruption investigation. But Hundley insisted that Hess' cooperation in Harford County was not related to Carey's allegations.

Carey said he never mentioned the charges before because his previous lawyers had advised against it. He said he relied on assurances by a public defender that he would "beat the rap" and never go to jail if he remained silent.

But Carey did go to jail, for one year, after pleading guilty to forgery and false pretenses. He admitted he embezzled $22,000 from the state inner-agency committee for public school construction (IAC), of which he had been appointed executive director by Mandel.

Carey said that Mandel told him that Hess would "represent the governor on all matters" related to the IAC, which set up offices in a building owned by the Hess-Rodgers Tidewater Insurance Co.

One of his first orders, Carey said, was to award a contract to Globe to build portable classrooms. But when it became apparent to Carey that Globe was not fulfilling its contract, he complained to Mandel.

It was at a meeting in June 1973, according to Carey, that either Hess or Rodgers offered him a $20,000 "bonus" if he would see that Globe retained the contract. He agreed, but said he never got the bonus because of the intervening federal investigation of the Mandel administration.

"I never met with him," Mandel said. Rather, the former governor recalled, Carey was the one "fighting for that contract" at appearances before the state Board of Public Works.

As an alternative to receiving the $20,000, Carey said Hess showed him how to embezzle $22,000 from the state agency. Carey admits he did that, although he contends he did not keep any of the money. Carey said he used the embezzled money to pay off debts that Mandel and his friends had run up on credit cards in Carey's name, because they wanted to "cover" their spending, which included many for a trip for Mandel and a girlfriend to the island of Aruba.

About the same time, Carey said, he pressured Globe for $3,000 which he contributed, under various names to a Four Star Salute that was the primary fund-raising event of Mandel's successful reelection campaign in 1974. It is that $3,000 that was the basis for Carey's second indictment, on charges of bribery and extortion.

Mandel said, "I have never been in Aruba in my life, and neither has Jeanne (his wife). And I never used one of Skip Carey's credit cards for anything. The only credit care I ever had was an American Express card that I used on official business only." Mandel repeatedly interrupted himself to scream about "these lousy lies."