A word was dropped in some editions yesterday from a quotation by Republican National Committee chairman Bill Brock.The quotation should read: "You can't not take something like this [the reports of bugging at RNC headquarters] seriously, but it is hard for me to believe this sort of thing happens anymore." In addition, the name of the Republican deputy was incorrect. He is Drew Lewis.

A search for electronic bugs in Republican National Committee headquarters here was halted last night after party chairman Bill Brock learned that a D.C. policeman entered the headquarters earlier yesterday without Brock's knowledge.

The search for possible bugs had gone on for about three hours before Brock ordered it stopped. Republican officials indicated tentatively that the electronics professional carrying out the sweep had found nothing.

About midnight, D.C. police formally took over the investigation from the private firm whose search had been halted.

Suspension of the electronic sweep was the latest in a series of bizarre events that provoked the suspicion that Republican headquarters may have been the target of electronic eavesdropping.

Last night's inspection followed an inconclusive report on Wednesday from two electronics experts that a magnetic field and suspicious wires found in the office of Republican co-chairman Mary Crisp could have been used for surveillance.

Although committee staff members knew of the Wednesday discovery, Brock said yesterday that through a staff mistake that "will not happen again," he did not learn of the finding until questioned Friday by a reporter.

Although some GOP staff members reportedly knew for some time of yesterday's visit by the policeman to the party's Capitol Hill headquarters, Brock apparently did not learn of Officer Larry Sterling's visit until late last night.

Subsequently, Brock ordered aides to telephone D. C. Police Chief Burtell M. Jefferson to find out why the offficer, attached to a technical unit of the morals division, was in the building without the knowledge of Brock and most of his top aides.

Officer Sterling said that he was sent to the headquarters in response to a request from Winston Norman, the GOP committee's security chief, but that he did not stay long or do anything.

The GOP security chief, according to Sterling, wanted to talk to an expert on wiretapping and the electromagnetic field. "I'm not [one]," Sterling said.

Sterling reportedly expressed the view that the wire discovered Wednesday was part of a system for piping recorded music into the building, one Republican official said.

At a news conference late yesterday afternoon, facing evidence consistent with several techniques of electronic surveillance but still inconclusive, Brock said, "You can not take something like this seriously, but it is hard for me to believe this sort of thing happens anymore."

Asserting that "I don't think anyone in the [Republican] party would do anything like this," Brock went on to say that he found it "a remarkable question why anyone would want to bug anyone in this building. . . . There are paranoid individuals. . . . But I find it very difficult to think that anyone would believe there are secrets here worth that kind of effort."

Shortly before 6 p.m. yesterday, security consultants from the firm of Interspec Inc. entered the national committee building at 310 First St. SE and carried their sensitive equipment to the fourth floor where Brock and his top political assistants have offices.

The firm -- which Republican officials acknowledged has made routine "sweeps" for electronic bugs in other GOP offices in the past -- was hired to search Crisp's office and an adjoining office for any evidence of electronic surveillance.

Last week's discovery of the errant wire and the mysterious magnetic field came during a period of enormous tension within the Republican committee, amounting, one official said, "almost to paranoia."

In preceding weeks, a campaign had been mounted by influential conservative advisers to likely Republican presidential candidate Ronald Reagan to oust Brock from the national chairmanship and replace him with a Reagan loyalist.

Mary Crisp, an Arizona feminist, national committeewoman and the party's cochairman had become an even greater target for the party's conservative wing.

Crisp is a strong supporter of the Equal Rights Amendment, which Reagan opposes. Crisp has also made several public statements about the candidacy of independent presidential candidate John B. Anderson of Illinois that have annoyed Reagan supporters. Two weeks ago, Crisp announced that she would not seek reelection.

Ben Cotten, Brock's political director, who occupies the office between Brock and Crisp, had also fallen into disfavor with the conservatives.

The most recent previous electronic "sweep of the Republican offices occurred in May, officials said yesterday. At that time, only Brock's suite at the north end of the building and the smaller office of Cotten were checked, according to press secretary Linda Gosden.

Last week's electronic inspection of Crisp's office was initiated by Crisp, without consultation from other Republican officials, after she said she heard strange "beeping" sounds on her home and office phones.

One of the most puzzling aspects of the still inconclusive finding of possible eavesdropping is the failure of seven staff officials to tell Brock about the sweep.

As reconstructed yesterday in numerous interviews, the knowledge of Crisp's private detective work and its results followed this course:

Crisp's assistant, Cathie Hogan, accompanied the two electronics experts on their Wednesday search of Crisp's office. Hogan informed national committee lawyer, Donald Ivers, of the inconclusive discovery on Thursday.

Ivers in turn inspected the office with Larry Kettlewell, a Cotten assistant, and Harland Strauss, another committee staffer who had first sought out the experts on behalf of Crisp.

Kettlewell informed his boss, Cotten, who was out of town and the next day he also informed Gosden, the press secretary.

She told her boss, Michael Baroody, Brock's assistant for public affairs.

None of them apparently felt it was necessary to inform Brock. "We didn't notify him because we felt the evidence was so inconclusive," said Baroody early yesterday. Later, however, Baroody and Gosden said they felt they had made a mistake in judgment, but Kettlewell and Baroody said they were skeptical about the evidence and felt the situation would be resolved by calling in the committee's own security consultant for a second opinion.

Baroody also said that during the two days following the discovery, staff members neglected to contact the consultant. "At the staff level, that didn't take place . . . It's pretty difficult because of the limited number of people capable of conducting one of these (sweeps)," said Baroody.

"They [staff members] just took it on their own initiative to treat it routinely," said Brock. "I fussed at them last night and again today about it -- they took it lightly," he said.

The somewhat bizarre drama of the possible bugging began last April when, Crisp says, she began to hear the "beeping" tones on her home phone at the Shoreham Hotel. Moreover, this month Crisp said she heard similar sounds in two conversations on her office telephone.

After discussing the noises with two friends, Crisp said she sought out "someone I respect who is involved in intelligence." That person, she said, recommended that she contact Richard E. Govignon, a 34-year-old Army reserve intelligence officer.

But Govignon also sought additional help. He contacted George Lesser, an electronics expert who works for Interstate Bureau of Investigation, Inc., a Baltimore-based security firm.

The two experts set to work Wednesday morning. They arrived at Crisp's Shoreham Hotel apartment at 8:30 a.m. and worked for four hours, examining her telephones, searching bookshelves -- even the books themselves -- and they disassembled one or more clocks. They found no evidence of electronic surveillance in her apartment.

Early Wednesday afternoon, Govignon and Lesser arrived at the Republican National Committee building at 310 First St. SE and began a similar investigation of Crisp's fourth floor office. That inspection lasted until 2 a.m. Thursday.

Crisp's staff assistant, Hogan, accompanied the men while they worked. They first discovered a white, double strand of wire that traversed the ceiling in Crisp's office, hidden by acoustical ceiling tiles.

Lesser told his boss at Interstate that the wire ended with a jack that could have been attached to a listening device.

The opposite end of the wire dropped down from the ceiling into the north wall of Crisp's office, which joins the former office of Barbara Carmichael, another Crisp aide.

As of Wednesday, Carmichael's office was assigned to Reagan deputy campaign director Dean Lewis.

The second discovery during the late night sweep was an unexplained magnetic field that appeared to be "focused" on the airspace within a few feet of Crisp's office desk.