Three felony cases involving the theft and distribution of D.C. government vehicle inspection stickers have been dropped because of a prosecutor's error in the processing of the court papers, a spokesman for the U.S. attorney's office said yesterday.

The cases were the culmination of a 19-month investigation by the Public Integrity Branch of the D.C. police department. The arrests of one employe of the city's Bureau of Motor Vehicle Services and two other men for trafficking in stolen property were announced by Capt. William Ritchie, who heads the Public Integrity Branch, at a news conference Tuesday. Four hours later the three men were free.

The city employe arrested and later released was responsible for stealing 3,000 inspection stickers from a government storeroom, police said.

According to the affidavit filed in D.C. Superior Court, the man was filmed on a hidden video camera taking the stickers from 301 C St. NW. The same man was seen selling the stickers for $20 each to a police informant.

"I am not as upset as I was last night," Ritchie said of the error on the part of the U.S. attorney's office.

Clendon Lee, spokesman for the U.S. attorney's office, said, "The temporary dismissals have had no practical effect on the prosecution of these cases. They will be referred to the grand jury for its consideration."

A source close to the U.S. attorney's office said that such errors are unusual.

On Tuesday, D.C., U.S. Park and National Airport police checked more than 2,000 taxis at a dozen places looking for drivers without a hacker's license and stolen inspection stickers. Most of the 50 cabdrivers arrested in the crackdown, dubbed Operation Back Alley, were charged with possession of stolen property.

Eighty cabs were seized as evidence. Yesterday about 50 of them were lined up in two long rows at a police impoundment lot at Second and Q streets SW.

Because of a difference in local laws, drivers of the cabs seized at National Airport were arrested. In the District, police did not arrest the drivers using leased cars that displayed stolen stickers but did seize the cabs.

Yesterday there appeared to be fewer cabs than usual on the streets of Washington and even the chairman of the D.C. Taxicab Commission had problems finding taxis during the day.

"I couldn't find a cab today near a downtown hotel," commission Chairman Arrington L. Dixon said. "It is only a temporary situation. I think the drivers are waiting to be sure the police operation has ended."