Although Charles F. C. Ruff may best be remembered for the bigger cases he supervised as U.S. attorney here--such as the prosecutions of congressmen involved in the Abscam bribery cases, local judge Robert Campbell, and convicted killer Bernard Welch--Ruff also will leave a less-public legacy.

He calls it his "never-ending agenda." Since taking office in 1979, Ruff tried to improve the U.S. attorney's handling of local prosecutions. To do that, he first did his own internal investigation of office policies.

What he found was startling: not only did the enormous caseload overburden his prosecutors, but his own office essentially was making things worse by preparing each case twice.

"The fact that felony prosecutors believe that the grand jury prosecutors' section sends them cases with fatal trial defects," Ruff was advised in a strongly worded internal memorandum, "has led to a lack of confidence in the grand jury section attorneys .

"As a result, felony prosecutors tend to ignore the work done by grand jury assistants and to prepare cases all over again, as if the earlier work had never been done," the report said.

"In short, most felony trial prosecutors expressed the concern that they were being needlessly innundated with mis-charged or ill-prepared cases that prevented them from devoting time and energy to prosecuting serious crimes."

Of the nation's 94 federal prosecutor's offices, only Washington's is responsible for the prosecution of local offenses. And according to the latest Report of the United States Attorney for the District of Columbia, the caseload is growing. In 1980, (the latest statistics available) more than 15,000 D.C. felony and misdemeanor crimes were prosecuted. That figure is increasing faster than the number of dispositions, too, and the length of time from indictment to disposition has risen.

Ruff then dispatched two deputies, Gordon C. Rhea and Dan Seikaly, to 10 cities to examine the operations of other local prosecutors' offices to seek ideas. Rhea and Seikaly also surveyed veteran prosecutors in Superior Court. Their report, obtained by The Post, became the subject of heated internal debate.

"What we tried to do was take a look at the work of the office and decide what the priorities were," said Rhea, "As a result . . . we decided that more resources should be put on the more serious offenders, which meant beefing up the unit handling repeat offenders and strengthening the felony intake section."

Ruff did make some changes: to improve the screening of cases, he assigned senior attorneys to the grand jury section to supervise case intake. The "Career Criminal" recidivists unit was beefed up. The victim/witness unit was upgraded, with special attention given to the problems of sexual assault victims. Diversion programs were expanded and, while Ruff was in office, the growing backlog of misdemeanor cases was held in check for a time.

Rhea's study suggested broad changes, such as an "open discovery" arrangement by which defendants would be allowed a complete and early look at the government's evidence against them in return for a strictly enforced, graduated plea-bargaining system in which the government's deal would get stiffer as time passed.

"An efficient system should offer a carrot and a stick to defendants who intend to plead . . . at the earliest possible moment," Rhea advised in one memo.

But the concept was hindered by what Rhea called a "lack of coordination among sections" and a "lack of confidence that prosecutors in one section have for those in others."

"There is no mechanism for ensuring that realistic pleas are made early in a case . . ." Rhea's memo said. "While most prosecutors feel that early discovery is necessary for early pleas, felony prosecutors do not trust grand jury prosecutors to give discovery. As a result, discovery is rarely given at an early stage, and cases that could have been disposed of . . . are passed on to the felony section, swelling its case load."

Ruff acknowledged that less-experienced prosecutors sometimes are reluctant to open their files to defense attorneys because "by giving too much you can always get burned," but he supports the idea as a way of making the system more efficient.

He also wanted to expand the concept of "vertical prosecution," where a single felony prosecutor would handle a case from the grand jury stage until trial. This would save money on court appearances by police and witnesses and reduce the number of prosecutors with whom victims must deal.

Recently, under a plan developed by Superior Court operations director Ed Ross, the felony division began reviewing all felony grand jury indictments. But except for the repeat offender unit and one experimental project, "vertical prosecution" still is in the planning stages. Some prosecutors object to it on grounds that the best lawyers should be trying already developed cases, not investigating them from the outset.

In an interview before leaving office, Ruff stressed that his ideas do not require "drastic changes in the system" but rather "nudging the system here and there, changing the emphasis.

"To the extent that I see my two years as marked by anything," Ruff said, "it is that I started the practice of asking those questions, to see if there are better ways of doing things.