A nine-year veteran D.C. police officer who worked part of the time as a plainclothes narcotics officer was arrested yesterday on federal charges of trafficking cocaine during the last decade.

Officer Andrew James McGill Jr., 29, of Forestville, was arrested by U.S. Drug Enforcement Administration agents and District police officers as he went to work at 3 p.m. at the 5th Police District in Northeast Washington, Executive Assistant Chief Terrance W. Gainer said.

Yesterday's arrest marked the third time in less than 10 days that a D.C. police officer has been accused of a crime.

On Tuesday, Officer Darrell L. Green, a seven-year police veteran, was arrested on charges that he looted a self-storage unit in Vienna. Last week, Officer Warren L. Pindell, a nine-year veteran, was charged with two counts of armed robbery after he allegedly held up prostitutes' customers. And in October, someone stole money from a safe in the 4th District station.

"There are 3,545 police officers who are out there doing a very good job tonight," Gainer said. "But there are a few bad apples, and we will continue to weed them out."

McGill and three suspected cohorts, who also were charged, had been the subject of a months-long investigation by the FBI, DEA, D.C. police and Maryland U.S. attorney's office, Gainer said.

It was not immediately known how much cocaine McGill and the others allegedly trafficked, although Gainer described the amount as "substantial." Indictment papers did not disclose precisely where McGill allegedly sold and arranged the sale of the drugs, other than to say it was in Maryland, Gainer said. Lynne Battaglia, the U.S. attorney for Maryland, announced the indictment but could not be reached for comment last night.

Also indicted were Erskine Hartwell, Basem Najjar and Jeffery Ewing, Gainer said. None is a law enforcement officer, Gainer said.

The four were indicted recently by a grand jury in Greenbelt on charges of conspiracy to distribute dangerous substances from 1989 to May 1999, Gainer said. If convicted, each man faces up to 40 years in prison and a fine of up to $4 million, Gainer said.

McGill joined the D.C. police force in July 1990, said Officer Kervin Johnson, a police spokesman. McGill first worked in the 7th District in Southeast Washington, where he served for a time as a plainclothes officer, policing the trafficking of guns and narcotics, according to 7th District officials. He later was transferred to the 5th District.

"It was obviously a long and continuous drug conspiracy," Gainer said. "The implication is that they had an ongoing enterprise to sell the drugs."

McGill's police powers have been revoked, and Gainer said the department was moving to have McGill fired. Under the department's union contract, McGill will be given 14 days' notice before his pay is revoked, Gainer said.

"Chief [Charles H.] Ramsey is clearly disturbed that a member of our department would be engaged in this criminal activity. There is no room on the [police force] for crooked cops," Ganier said.

Some officers at the 7th District said they had been leery of McGill. "He wasn't good news for this place. Nobody wanted to work with him," said one officer who didn't want to be named.

Another officer disagreed. "He was a friendly, nice guy. I would have never have guessed he would do anything illegal. He never did anything to make me believe he was anything but a good police officer," he said.

In unrelated cases, Officer Darrell L. Green, 28, turned himself in to District police Tuesday after authorities in Fairfax County accused him of stealing paintings, antiques, china and Oriental rugs worth several thousand dollars from a Vienna self-storage unit.

Last week, Officer Warren L. Pindell, 33, was charged with two counts of armed robbery after 4th District detectives followed up on a report from a prostitute's customer who said Pindell held him up and took his cash.

And in October, D.C. police began investigating the theft from a safe in the 4th District of proceeds from a fund-raiser to benefit the family of an officer who had died of cancer.