For a year, a man known only to his customers as the "Candy Man," supplied brightly colored drug capsules bought by hundreds of Northern Virginia students for as much as $4 a pill in school corridors and washrooms, according to police.

But the purported Candy Man, who used business cards decorated with pictures of powerful amphetamines and babiturates that urged users to "get high and fly," had a secret -- the pills were fakes.

"They were nasal decongestants, or caffeine that wasn't any stronger than yesterday's coffee," said a Fairfax County narcotics investigator.

Last Saturday, after a year-long, undercover investigation, Fairfax County police arrested a 31-year-old Stafford County resident named Carl Edgar Bennett, who they say was the "Candy Man," and charged him with a series of offenses in connection with the sales.

These sales, which led to Bennett's arrest, the first of its kind in Northern Virginia, are believed by police to be part of what federal drug officials say is an alarming "nationwide, multimillion-dollar rip-off" of would-be drug purchasers.

"The drug rip-off has become a major business of its own," said Sgt. R. L. Bennett of Prince William County, who said narcotics officials found business cards identical to Carl Bennett's in Dale City and Woodbrige.

"They (the pills) are distributed in schools on almost a daily basis. We caught a 15-year-old with 200 of them just last week."

Federal and local authorities say the fake narcotics, while often harmless in themselves, encourage use of addictive drugs, and may lead to overdoses when such drugs are ingested.

"The problem is, you have no idea what you are buying," said Ron Buzzeo, chief compliance officer of the federal Drug Enforcement Administration. "We're picking up a tremendous number of these pills on the street, and it takes an expert to tell them from the real thing."

According to police, Bennett, acting through unidentified go-betweens, allegedly flooded Northern Virginia with several thousand fake pills that eventually found their way to school-children as young as 10 years old.

The pills, which police said were obtained wholesale from a Pennsylvania manufacturer, were sold to unsuspecting youths as powerful stimulants and depressants with such nicknames as "yellow-jackets," "black beauties," "robin's eggs" and "speckled birds."

"The suspect boasted that he could get 450,000 pills on short notice, which he would sell in jars of 1,000 tablets for $90 to $100," said a Fairfax investigator involved in the case. "But there were other, intermediate pushers who would then sell groups of hundreds, like 300 'yellow-jackets' for $150."

From there, the investigator said, the pills were allegedly sold to student pushers at junior and senior high schools in the area in quantities of less than 100 pills; they in turn wouuld sell them in restrooms and hallways for up to $4 a pill.

Police said the pills allegedly sold by Bennett were traced to a drug manufacturer who mass produces the tablets to resemble controlled substances at a cost of less than 3 cents a pill.

Authorities in Prince William, Fairfax and Arlington counties, stymied by what they said are vast numbers of fraudlent drugs circulating in suburban Washington, said the problem persists because of the inability to prosecute such manufacturers.

"There is absolutely no doubt that these manufacturers know what these pills are being used for and where they wind up," said Fairfax narcotics squad Lt. Mike Young.

Illegality emerges only in the intermediate stage of the pill-selling chain, investigators said, when street dealers place fradulent labels on the pills and sell them as powerful, authentic narcotics.

Buzzeo of the DEA said federal oficials have contacted the Federal Drug Administration and the Federal Trade Commission to see if manufacturers of fake pills can be prosecuted on other charges.

Authorities have also been irritated by the arrogance of some dealers, one of whom recently called a Prince William County newspaper, the Potomac News, to suggest that he should be lauded "for keeping the real stuff away from youths."

"That's ridiculous," said a Fairfax investigator. "You let a kid pop five or six of these fakes, which may have litle effect, then he gets a real amphetamine and tries to take five or six of those . . . then it's all over for him."

According to a Fairfax drug investigator, Bennett was arrested after undercover officers made several purchases of fake narcotics allegedly set up from Bennett's former home on Trenton street in Arlington.

"It was a situation where we could find these business cards and the fake pills on 75 percent of the drug raids that we were making," the investigator said. "I called the phone number on the cards and would leave an order for '500 black beauties' with the suspect, a woman, or the recording."

The purchases allegedly were made at the Yorktown Shopping Center at Rte. 50 and Gallows Road in Fairfax County, he said.

Bennett, who surrendered to Fairfax police last weekend, was free on bond from the Arlington County jail on a marijuana possession charge at the time.

He is scheduled for trial March 11 in a Fairfax courtroom on charges of obtaining money on false pretenses, removing labels from drug containers, selling misbranded drugs, and failure to possess drug repackaging and relabeling permits.

If convicted, Bennett could face a $1,500 fine and up to 12 years in prison. He was released on $1,750 bond in the case last Sunday.