U.S. Attorney Russell T. Baker Jr. added another unexpected twist yesterday to the aftermath of former Maryland governor Marvin Mandel's political corruption conviction by recommending that a federal judge suspend the 18-month sentence of Mandel codefendant Ernest N. Cory.

In addition, while opposing the sentence reduction requests of Mandel and three other codefendents, Baker endorsed codefendant William A. Rodgers' motion to have his 20-month sentence cut.

Baker's proposals, contained in a four-page brief filed in U.S. District Court in Baltimore, were the culmination of discussions that began in the late summer of 1977 when the three assistant U.S. attorneys prosecuting the case were deciding what sentences to recommend.

All six defendants -- Mandel, Cory, Rodgers, his brother Harry W. Rodgers III, W. Dale Hess and Irvin Kovens -- were convicted of mail fraud and racketeering, but the prosecution team believed the effect of the case had been far more devastating on Cory than on his fellow defendants, according to sources familiar with the discussions.

At the same time, some government attorneys felt that William Rodgers had been less a participant and more of a hanger-on during the complex series of transactions that led to the federal corruption indictments.

These views were reflected in Baker's brief. In reference to William Rodgers, Baker wrote, "He was in many respects a passive, albeit knowing, beneficiary of a complex scheme which had been engineered and was being executed by several far more active, forceful and culpable individuals."

"Upon reflection . . . government counsel respectfully believe that full recognition of the . . . substantial distinctions between his criminal conduct and that of the other defendants justifies some reduction of his 20-month prison sentence."

Moving to the question of Cory's role, Baker wrote, "Cory's conduct in this matter was active, knowing and culpable. His personal culpability was aggravated by the fact that he was at the time a member of the bar; indeed, his role in the scheme was that of its lawyer."

But, Baker added, "The impact of the prosecution had been so personally devastating to him -- far more so than to any of the other defendants -- that his imprisonment would, in our judgment, be inhumane."

In his motion for reduction of sentence, Cory's attorney cited the fact that Cory had been disbarred and has lost his real estate license since his conviction in August 1977. He is now teaching sailing at the Nautilus Sailing Club in Annapolis.

Mandel voluntarily relinquished his law license after his conviction and now operates a consulting business with his wife, Jeanne, in a small office in Arnold, Md.

Baker acknowledged in his brief that the numerous unpredictable and contradictory twists of the 2 1/2-year appeals process in the case have led to "pain, suffering and stress" for all defendants in the case.

The six believed they had won their fight for vindication in January 1979 when a three-member panel of the 4th U.S. Circuit Court of Appeals reversed their conviction, but this decision was reversed by a tie vote of the full appeals court.

The U.S. Supreme Court ended the defendants' battle last week when it rejected their request to consider the case. Unless Judge Taylor acts to reduce or suspend any of their sentences, the six are scheduled to begin serving prison terms on May 14.

In opposing the sentence reduction motions of Mandel, Hess, Kovens and Harry W. Rodgers III, Baker said any suffering the four have undergone is the result of "their former positions of prominence and the magnitude of their offense: betrayal of the public trust."

To reduce the four-year sentences imposed on these four men solely because of the "prolonged and erratic appellate process," Baker said, "would be unfair to many other criminal defendants who have endured long post-conviction struggles . . .

"To reduce these defendants' sentences on that ground would undermine public confidence in the administration of justice by enhancing the . . . widespread cynical attitude that there is one system of justice for the prominent and wealthy in our society and another for ordinary citizens."

The Rodgers brothers, Hess and Kovens were all powerful and well-connected businessmen when the investigation into the case started. They have all maintained their business interests.

The four men, along with Cory, were convicted of providing Mandel with $350,000 worth of gifts and favors in return for his taking favorable actions enhancing the value of the Marlboro Race Track, which they secretly owned.