On May 9, the day the Maryland public learned that he was conducting a criminal investigation of a Baltimore savings and loan, state Attorney General Stephen H. Sachs received what he called an "old times' sake" telephone call from former Democratic U.S. senator Joseph D. Tydings.

The subject: "Prosecutorial nostalgia," said Sachs.

For the past three weeks, as official Maryland scrambled to cope with a massive crisis of confidence in the savings and loan industry touched off by the problems at Old Court Savings and Loan, Sachs has been awash in distant memories. Over and over he has been reminded of the savings and loan scandal of the early 1960s, when as a young assistant U.S. attorney he helped his boss Tydings prosecute and send to jail a number of prominent politicians.

The current, and still-unfolding, savings and loan saga "is redolent of 20 years ago," said Sachs. "The idea of the same industry in trouble and a regulatory apparatus that is broken down and the suggestion of wrongdoing -- these are similarities. What we don't know is what the outcomes will be."

Sachs leaves unsaid another similarity -- the opportunity for political gain.

For Sachs' political supporters, the Old Court investigation, with its promise of well-publicized indictments and prosecutions, represents a chance for history to repeat itself. Just as Tydings' high profile role in the 1960s scandal helped propel him to the U.S. Senate, they say, so could Sachs' handling of the Old Court probe boost his chances of becoming governor in 1986.

Sachs, sensitive to charges he already has exploited the situation for political gain, is reticent on the subject. "To talk about it in political terms is to give credence to the suspicions that political motives intrude," he said. "You have to shut out political considerations and do your job, and p.s., that is the best politics."

But those who are committed to making Sachs Maryland's next governor talk openly of the opportunity afforded by the Old Court investigation to narrow the gap between the attorney general and his strongest likely opponent, Baltimore Mayor William D. Schaefer.

Although Schaefer has not committed himself to the race for the Democratic nomination, he has scheduled a massive political fund-raiser for September and it is difficult to find a politician in the state who does not believe he will join the Democratic field already occupied by Sachs and House of Delegates Speaker Benjamin L. Cardin.

The savings and loan investigation, which is likely to keep the attorney general in the spotlight for many months, "puts Steve Sachs in his element," said his campaign manager Blair Lee IV. "He's a prosecutor, he's a cop, and his whole political history and governmental history has been one of a reformer . . . . He is much more effective in that posture than he is talking about higher education or state employment policy."

For Sachs, a 51-year-old whose energy is equaled by his ego, the Old Court investigation presents the chance to benefit politically from what he likes doing best -- prosecuting alleged wrongdoing. Sachs' love for the legal chase is such that one of his political allies suggested recently that if he could be guaranteed a regular diet of Old Courts, Sachs would be content to remain as attorney general.

Sachs disagrees with that assessment but concedes that the Old Court investigation is "the kind of task I feel both comfortable with and am expert at."

Despite the potential of the Old Court probe, most political observers, including Sachs partisans, admit that he has a long way to chase Schaefer, the enormously popular four-term mayor who is as much a symbol of his city's rebirth as Harborplace.

For example, a poll published Friday in the Daily Record, Baltimore's legal journal, shows that Schaefer is known by 87 percent of the registered voters surveyed around the state and is viewed favorably by 62 percent.

Sachs is known by 80 percent and seen in a favorable light by 50 percent. And while Sachs' figures have remained static since the paper's poll 13 months ago, Schaefer has gained in both recognition and favorability. Cardin trails far behind, with a 38 percent recognition factor and an 11 percent favorable rating.

And although a Daily Record poll on Thursday showed that Marylanders approved by a 3-to-1 margin Sachs' controversial announcement of the criminal probe, he could be vulnerable on that score. Many of the attorney general's political foes, including Schaefer, criticized the announcement as inflammatory and contributing to the erosion of public confidence in the industry.

Many legislators were reluctant to give Sachs the power to grant immunity to witnesses in the Old Court probe, fearing that it would give him a windfall in his campaign. However, he eventually won that authority as part of a compromise agreement that included creation of a special counsel investigation of the state's oversight of the thrift industry.

It is impossible to gauge how the continuing investigation will affect Sachs' political fortunes.

"I don't see a down side for Sachs," said state Sen. Thomas V. Mike Miller, (D-Prince George's), an unabashed Schaefer supporter. "Public sentiment is such that it needs a wrongdoer. Steve Sachs has a golden opportunity to not only find that person but to bring him to justice. It will tighten the race for a while."

But Miller and others hostile to Sachs' gubernatorial campaign are already probing for soft spots in the attorney general's role in handling the crisis and in regulating the savings and loan industry. They are pinning their hopes on the special counsel investigation.

Sachs, observed Miller, "had attorneys advising the savings and loan division. He had attorneys assigned to the consumer protection division. If he's going to take credit for the sunshine, he's going to have to take credit for the rain."

"Questions are going to be raised about various officials' roles in how this could have been prevented and officials' roles in exacerbating or containing it," predicted Bruce C. Bereano, an Annapolis lobbyist who supports Schaefer.

Tydings, who credits his own savings and loan prosecutions with giving him "credibility" in his successful 1964 Senate bid, said that Sachs "has to deliver" if he is to benefit from the Old Court probe. "If he does a good job, then it will increase the confidence people have in him. If he messes up . . . he suffers the consequences."

But Tydings also says Sachs' position is inherently more treacherous than his own was in the early 1960s because as attorney general. Sachs also must serve as counsel to the governor and other state officials "responsible for straightening out the industry." If the state ends up with a major financial burden imposed on it by Old Court or other troubled thrifts, Sachs will share the blame, Tydings says.

Even with those risks, however, Sachs' supporters believe that their candidate will almost certainly benefit from the savings and loan situation.

"Politically, it's a plus," said Del. Albert Wynn (D-Prince George's). "It adds to his stature."

Lee, Sachs' campaign manager, predicts that the issue will highlight the different approaches to government of Sachs and Schaefer. "It undercuts the Schaefer theme of blurring government and business into one entity, of discarding process and regulation, of getting things done and to heck with the red tape," said Lee.

"Sachs is more of a process person who believes there has to be a referee and a regulator keeping an eye on things. Clearly, in this situation, the regulators did not regulate."

"This," concludes Lee, "is a home game for him."