The grisly suicide of former Queens Borough president Donald R. Manes removed a major target of corruption investigations here, but indictments of other officials are expected within weeks, and more than a dozen other investigations will continue, federal and city prosecutors said today.

Manes, 52, one of the most powerful politicians in the city until his resignation five weeks ago, stabbed himself to death with a kitchen knife Thursday night. The suicide came more than two months after an initial suicide attempt and three days after Manes' former protege, Geoffrey Lindenauer, pleaded guilty to reduced charges of racketeering and mail fraud in exchange for testifying against Manes and other city officials.

Lindenauer, former deputy director of the city's Parking Violations Bureau, admitted accepting $410,000 worth of bribes from collection agencies doing business with the city. One of the agency owners had told federal prosecutors that he paid the bribes on Manes' orders.

U.S. Attorney Rudolph Giuliani, whose investigation led to Manes' abrupt fall from power, called his death "a terrible tragedy." However, he said, "In practical terms, it has no substantive effect on the investigation. It doesn't mean that something we could have done can't be done or vice versa."

Giuliani is investigating other parking bureau officials, and officials at the city's Taxi and Limousine Commission, the Board of Education and other city agencies.

He and Manhattan District Attorney Robert M. Morgenthau are jointly investigating the role of Bronx Democratic Chairman Stanley Friedman, another powerful city official, in the awarding of a city computer contract to a firm partly owned by Friedman.

Four other district attorneys, the city investigations department and a city council investigator, the State Attorney General and the City Board of Ethics are conducting separate corruption inquiries.

Late today, former U.S. Attorney John S. Martin Jr., head of a special corruption investigations commission appointed by Mayor Edward I. Koch on Jan. 20, quit and dissolved the commission, saying it overlapped other federal and city inquiries.

The Associated Press reported that a city employe was found hanged in an office in Queens Borough Hall. There was no indication that the deaths of Richard Roth, 53, an assistant civil engineer, and Manes were related, police said.

U.S. Attorney Raymond Dearie, who divides city jurisdiction with Giuliani, said of Manes' suicide: "I don't believe it is going to have a serious impact on the probes . He was a target. Now the attention devoted to him might be directed at others."

While speculation has centered on whether Manes might have cooperated with investigators if he had been indicted, and whether he might have testified against other officials, city and federal investigators today gave no indication that such a possibility had been discussed.

"There was no reasonable indication he was going to be offering everyone information," Dearie said. "Indications were he was digging in and was going to fight any charges that might have been brought against him."

Dearie is investigating alleged payoffs in the city's Environmental Control Bureau, the efforts of Manes and others to create a Grand Prix racetrack in Queens and allegations that a chief Manes aide took kickbacks to arrange court guardianship and conservator appointments.

Michael Armstrong, Manes' attorney, who spent most of Thursday afternoon with him, said Manes had been so severely depressed that "he couldn't make the choices . . . to defend himself rationally."

In a news conference today, Koch, who had called Manes a "crook" during the early stages of the investigations, said that the charges were "water over the dam . . . . I prefer to remember the good things Donald Manes did over a very long career . . . . I don't regret my friendship over 20 years."

Manes, a close friend and political ally of Koch, was known as the "King of Queens." He ran the Democratic machine that hands out judgeship nominations and numerous political patronage posts within city government.

He was a large man with a quick sense of humor and a talent for political wheeling and dealing. When he first attempted suicide on Jan. 10 -- police found him in his car in the middle of the night bleeding from self-inflicted cuts on his wrist and ankle -- friends and associates were astonished. That attempt came as prosecutors closed in on Lindenauer.