On the night of Oct. 20, a pickup truck with Virginia tags pulled into a driveway in a subdivision on the outskirts of this Howard County seat. As four men began unloading cardboard cartons from the back, police moved in, seized 520 pounds of marijuana said to be worth $375,000 and took the men into custody.

It was, police said, the largest marijuana bust in the history of Howard, a once largely agricultural county now dominated by Washington and Baltimore commuters.

The newspapers, relying on an official press release, reported that four men had been "arrested," that one had been "released" to the U.S. Drug Enforcement Administration "for charging" while another was "released to authorities from New Jersey on charges of assault with intent to murder."

The only problem was the two men had not been arrested and their given names were fictitious. They were, in fact, an informant and an undercover policeman. The Howard County police had issued a "cover story," they later tried to explain, to protect the safety of the two men and the integrity of two related investigations they hoped would lead to more arrests.

After stories appeared revealing the false nature of the original report, police say they had to cancel the other investigations they contended had been "compromised" by the publicity. "It was called to a halt because of the press," said Police Chief Paul H. Rappaport. His department's only error, he asserted, had been to put out a cover story -- details of which he said he had not reviewed beforehand -- that was "too unplausible."

"The press uses a number of terms -- lying, facade, misrepresentation. To me, it's none of that," said Rappaport, a former state policeman and an attorney. "I never lie to the press. I don't consider it a lie . . . . It's an extension of a covert investigation."

Whatever it's called, journalists in the area have reacted to the official deception with anger and indignation, complaining they were deliberately misled into printing inaccurate information and misinforming the public. Fragile relationships of trust between reporters and law enforcement authorities have been seriously strained if not permanently damaged. And basic questions have been raised about official use of the press in the conduct of criminal investigations.

Here in Howard County, the county executive and the chief prosecutor have closed ranks behind the embattled Rappaport. The whole affair, noted State's Attorney William Hymes, is the talk of the town.

The Howard chief's assertion that the practice is not only defensible but widespread among law enforcement agencies was rejected by other officials in interviews. "Withholding information outright is the best way to go," said Robert Angrisani of the International Association of Police Chiefs.

"I wouldn't fabricate a story," said Arthur DiGennaro, Prince George's County police spokesman and a former deputy chief of the D.C. Police Department. "I'd just pray to God the press wouldn't find out about it."

The story behind the story began in a routine way, with Cpl. Randolph W. Roby, the department's public information officer, contacting reporters the morning after the arrests to apprise them of the event. He read them a press release containing the fictitious elements hastily concocted by narcotics detectives the night before.

Those arrested, according to the release, were Frank J. Schittino, 19, of Ellicott City, Joseph Loverde, 30, of Baltimore, Wayne Larry Roberts, 28, of New York, and Andrew Jackson Hines, 25, also of Ellicott City but with only a post office box for an address. All were said to be charged with possession with intent to distribute marijuana. The first two were held on bonds of $155,000 and $150,000. The others were said to have been released to federal or New Jersey authorities.

A few paragraphs reflecting the official version appeared in the late edition of that afternoon's Baltimore News American. Similar reports appeared in the Baltimore Sunpapers and also in three weeklies, the Howard County News and the jointly owned Columbia Flier and Howard County Times.

The official version began to unravel after Richard Burke, the News American's Howard County reporter, was assigned to do a follow-up story. The New Jersey angle did not check out, and Burke said the information he got from DEA on the other alleged suspect "didn't add up." He remembered, too, that an individual with a similar name had been charged in another arrest involving drugs months before.

Burke then called Roby for clarification. In a conversation Roby says was off the record and Burke says was on the record, the police spokesman told the true story, then pleaded with Burke to withhold publication. Burke said he would confer with his editors. Several hours later, Roby initiated a conference call with Burke and the head of the narcotics squad, during which the police request was renewed and rejected.

The decision to print the story was "pretty cut and dried," News American managing editor William Ward recalled. "Newspapers everywhere have become used to the fact that police will withhold full information," Ward said. But "by releasing false information to us" which was then published, he said, "they put us in a position where we really had to rectify the facts for our readers the next day."

The News American's second-day story discussed the deception involving the officer but said of the "third suspect" only that "police would not release his name."

Also unhappy about the misinformation was Tom Graham, news editor of the Howard County Times and Columbia Flier. After the News American disclosures, Rappaport had asked Graham to delay publishing the same information, in an attempt to limit its dissemination. Graham agreed.

But when the Evening Sun printed a correction of its earlier report, Graham said he felt "this further compromised our position" and asked to meet with the police chief. The two disagree on both the ground rules and content of their hour-long discussion. Rappaport says it was off the record. Graham disagrees. Rappaport said he told the newsman the other investigations would still proceed but "cautiously" in light of the disclosures. Graham said he believes the chief asserted the investigations had been too compromised to continue.

In any event, the next editions of the two weeklies featured news stories and an editorial entitled, "Why Cops Lie, Why We Can't." In the editorial, Graham outlined his paper's actions and ultimate decision to publish.

"Newspaper work is important, we feel, and it's necessary to tell the truth when we know it," Graham wrote. "Rappaport doesn't appreciate that. Even if we see through next week's cover story, he would have us print it -- lies and all -- because it will serve the causes of law enforcement.

"So the cops will continue to lie, and the press will continue to try to tell the truth, and both parties will feel that they're acting responsibily," Graham wrote. "No wonder we don't get along too well with the police."

In a letter to the editor published Thursday, Rappaport charged that Graham's "expose has placed an individual's life in further danger and has completely curtailed an ongoing major narcotics investigation." He also accused the editor of doing "a disservice to your profession and to the citizens of Howard County."

The letter prompted publisher S. Zerke Orlinsky to denounce the chief for questioning his editor's integrity. "We will not be abused by the chief of police," Orlinsky pledged in the paper. The paper had delayed publication to protect the police, he added.

"I in no way want to jeopardize a police investigation or lives of their undercover agents," remarked the News American's Burke, "but I don't feel I or any other member of the press did that. They planned this poorly. They assumed what I did through routine reporting criminals couldn't do the same."

For his part, Rappaport said he would follow the same course in the future "where it was absolutely necessary." In an interview, he could not recall another specific instance since his appointment in 1979 where the same thing had occurred. Roby, his spokesman, said, "I can assure you the other two years' releases have been 100 percent factual to my ability."

Both Roby and Burke agree their relationship has been tarnished. "They feel they're doing their job and we feel we're doing our job," Burke said. "All the feedback I get is that some of us reporters are in the doghouse right now, but that's life."

Roby also feels stung and hopes his credibility hasn't been irreparably damaged. "It's water over the dam," said Roby, "but it's a little turbulent down at the bottom of the pool."