Members of the D.C. police department's 4th District vice squad reacted angrily yesterday to the decision of U.S. Attorney Joseph E. diGenova to drop from 300 to 400 pending drug cases, saying the action leaves the impression that the entire 16-member unit is corrupt.

DiGenova said he made the decision because members of the 4th District squad are the subject of an FBI investigation of alleged thefts of drugs and money from drug dealers. Sources have said the bureau is focusing on four or five members of the unit.

Gary Hankins, chairman of the Fraternal Order of Police labor committee, called diGenova's decision "a cheap shot."

"We don't believe that he's acted properly," said Hankins, speaking on behalf of the officers at an impromptu news conference. "Our opinion is that they have taken the opportunity to dump hundreds of cases off of their calendar . . . . We don't feel it is a fair reflection of the officers of the 4th District vice unit."

Other police officers said privately that the dropping of the vice squad's cases was particularly disturbing because the cases tended to involve drug dealers and not those who were simply arrested on charges of drug possession. Most of the vice squad's cases, the officers said, were the product of substantial investigation. According to court records reviewed yesterday, the dropped cases represented about one-tenth of all drug cases pending in D.C. Superior Court.

It appeared yesterday that the number of 4th District drug cases to be dropped may grow. D.C. Corporation Counsel Frederick D. Cooke Jr., who is in charge of prosecuting cases in juvenile court, said his office would look at 4th District juvenile cases individually and could drop those open to challenge by defense attorneys.

Mayor Marion Barry, in a morning appearance on WOL-Radio, also said diGenova was wrong to drop cases that involved officers who are not under investigation.

He said the action would "allow people who are major drug dealers back on the street."

DiGenova said in a prepared statement yesterday that he had no choice but to drop the cases and suggested that some of the charges may be reinstated later.

"As officers of the court, our obligations are clear and unequivocal," diGenova said.

"These cases must be dismissed at this time. If any of them can be salvaged in the future, they will be."

Hankins said that he met with Police Chief Maurice T. Turner Jr. yesterday and that Turner told him that the entire 4th District vice squad -- 12 officers, three sergeants and a lieutenant -- would be temporarily reassigned pending the outcome of the FBI investigation.

Hankins said the chief's decision was forced by diGenova's move to drop the cases, and he said it could increase the prevalence of illegal drug activity in the 4th District, which covers large sections of upper Northeast and Northwest Washington.

"We are already hearing from officers on the street that the word is that the U.S. attorney won't prosecute drug offenders in the 4th District," Hankins said.

"And I think Mr. diGenova's action has, in the short run at least, opened the 4th District community to increased drug activity. And I don't think that's fair to the people who live in the 4th District or to the members of the 4th District vice unit."

Turner could not be reached for comment yesterday.

Sources have said the chief is strongly considering such a reassignment.

Hankins made the remarks as he emerged from the FOP's headquarters with about 10 4th District vice officers.

Hankins said the officers, all of whom declined to comment about the FBI investigation, think diGenova's dropping of their cases has unfairly created the impression that the entire 16-officer unit is corrupt.

"There are no charges against any member of this vice unit. There are only allegations with regard to two of them," Hankins said, in a reference to officers Shelton D. Roberts and James Whitaker Jr.

Roberts, who is also known as Sugarbear, was not at the 90-minute meeting, but Whitaker attended with his attorney, G. Allen Dale. The two men were named in a subpoena of the unit's records.

Whitaker, who left the meeting before his colleagues emerged with Hankins, also declined comment. Dale said Whitaker "maintains that he is innocent, and he is innocent." Roberts was unavailable for comment.

Dale also criticized the dropping of the drug cases, saying it showed that the officers "are being presumed guilty."

"Anytime you presume guilt, it is of grave constitutional concern," Dale said.

DiGenova announced Wednesday that he would drop as many as 400 drug cases brought by the 4th District squad. On Sept. 9, a half-dozen FBI agents conducted a search at 4th District headquarters on upper Georgia Avenue NW and collected a vanload of documents.

The Washington Post, which disclosed the FBI probe on Aug. 27, reported last Friday that the FBI investigation was launched last year after agents were told of the alleged skimming and that one of the 4th District officers leaked information to drug dealers in 1986 shortly before a massive drug raid.

The 4th District vice squad, according to a statement by the unit's commander in a preliminary hearing in February, has been more active than any other in the city.

"The 4th District executes more warrants than any other unit I have ever worked with, and we normally execute usually a minimum of two warrants per day," said Lt. Winslow MacGill. "We average, I would say -- I don't know -- maybe six to 10 warrants per week."

Hankins, in defending the vice squad members, said it would be unfair to assume that the unusually large number of search warrants generated by the officers was an indication that they were doing anything improper.

"I don't think it's fair to assume that because you had a lot of productivity out of a unit that it was necessarily corrupt," Hankins said. "That's an assumption that these people were being driven by corrupt motives, and I don't believe that."

In addition, law enforcement officials said yesterday that they were unaware of any other cities where a prosecutor announced the dropping of an entire squad's case load when police corruption was alleged.

"We are not aware of this kind of situation," said Fred Boyd of the Police Foundation, a national organization.

In Brooklyn, N.Y., where 13 police officers were indicted a year ago on charges that they extorted money and drugs from narcotics dealers, a spokesman for the district attorney's office said there had been no systemwide dropping of cases.

"We've had no mass dismissals and no announcement of such," said Linda Sachs, who added that the cases have been reviewed individually. "If there is no other evidence, then the case had to be dropped. If there was other evidence, we have tried to salvage the case." Sachs said the prosecutor's office there had not kept track of the number of cases dropped.