INSIDE the locker of a narcotics cop, Philadelphia police officials recently made a shocking discovery: A cartoon of a man, half as an officer in uniform and half as a Klansman with the words: "Blue By Day - White By Night. White Power," according to police officials.

The officer, Scott Schweizer, who has arrested countless drug suspects in predominantly African-American neighborhoods, was removed from his undercover police duties and given a desk job earlier this month, authorities said.

The disturbing find triggered an internal probe that widened yesterday as investigators began to explore whether the scope of the case is limited to Schweizer or somehow broader.

"It's certainly of great concern that someone would even think it's appropriate or think it's OK to even put something like that in a locker," Police Commissioner Charles H. Ramsey said yesterday. "We don't condone that kind of behavior."

Schweizer could face administrative action ranging from a written reprimand to dismissal. Schweizer did not return a phone call from the Daily News and did not respond to a note left by a reporter at his Northeast Philly home yesterday afternoon.

Roosevelt Poplar, a vice president of the Fraternal Order of Police, Lodge 5, in Philadelphia, said he was aware of the investigation but did not know its scope.

"We have no idea what the investigation entails at this time," Poplar said. "We have to give every member the benefit of the doubt before we make any statements or come to any conclusion."

Schweizer, 33, joined the force in June 1997 and makes $54,794 a year, city payroll records show. He became part of the elite Narcotics Strike Force about six years ago. As an undercover, plainclothes cop who worked day and night shifts, Schweizer was part of a surveillance team that watched drug buys and locked up hundreds of suspected drug dealers. He frequently testified in court as a witness for prosecutors.

Now law enforcement and legal experts question whether Schweizer's alleged behavior could jeopardize drug cases in which he was the arresting officer.

The case against Schweizer began earlier this month after an officer saw the racist drawing on the inside door of Schweizer's locker and complained to superiors.

"The investigation involves obviously very inappropriate material," police spokesman Lt. Frank Vanore said. "The material itself was disturbing and it launched an immediate internal investigation."

Supervisors within the Narcotics Strike Force treated Schweizer's locker as a crime scene, testing the paper and inside door for fingerprints. Schweizer told investigators that he had been framed and that someone must have planted the derogatory cartoon in his locker, according to police sources familiar with the investigation.

But only his fingerprints showed up on the paper, and other tests showed that the material had been in his locker for some time, the police sources said.

Since early January, Schweizer has been reassigned to desk duty at Police Headquarters, 8th and Race streets. In his new assignment, he takes accident reports over the phone.

Initially, the investigation was supervised by Chief Inspector William Blackburn of the Narcotics Bureau. Yesterday, however, the case intensified and was handed over to Deputy Commissioner Richard Ross, who oversees the Internal Affairs Bureau, authorities said.

"Basically we discovered additional information that has to be investigated before we can come up with a conclusion to our findings," said Chief Inspector William Colarulo, of Internal Affairs. "We have more interviews to do based on the information that was disclosed to us."

Colarulo said there is no time frame for completing the investigation, which he declined to discuss further.

Rochelle Bilal, president of the Guardian Civic League, which represents 3,000 African-American officers in Philadelphia, said the union has been monitoring the Schweizer case since the start. She called upon Ramsey to "do the right thing."

"African-American officers know that we work in an institution that is inherently racist and we also know that some of our colleagues tend to get comfortable with bigot behavior," Bilal said. "We are hoping that the new police commissioner, like the old police commissioner, takes a stand when it comes to racism in this department, and we will closely monitor the situation as it pertains to African-Americans in the city."

Reached last night, Ramsey said the investigation is exploring whether other officers knew about the alleged material in Schweizer's locker and if so, whether they condoned it. But so far, Ramsey said that the case "looks like an isolated incident" and that there is "no indication" of others being involved.

"We'll see what the investigation uncovers and let the cards fall where they may," Ramsey said.

He also said that Internal Affairs is looking over arrests made by Schweizer.

"Just because he made the arrests, that doesn't necessarily mean that those cases are bad," Ramsey said. "You can't jump to that conclusion."

Cathie Abookire, spokeswoman for District Attorney Lynne Abraham, declined comment yesterday.

JoAnne A. Epps, a professor at Temple University's Beasley School of Law, who specializes in evidence and criminal procedure, said defense attorneys will likely salivate over the allegations against Schweizer, though getting a drug conviction overturned would require proof that the officer engaged in illegal activity.

"Treating black people badly is one thing; planting evidence on them is another thing," said Epps, who serves on the board of the Defender Association of Philadelphia and headed former Mayor John Street's Task Force on Police Discipline.

She added, "You don't win just because you were arrested by a racist, even if you would be able to prove it . . . But I think most defense attorneys would aggressively pursue this information. It's enormously troubling and enormously tantalizing, and it would be a mistake for any defense attorney to conclude that it's not going to go anywhere, even though it's a difficult burden." *

Staff writer David Gambacorta contributed to this report.