When the Fairfax County Board of Supervisors this week fired the head of its purchasing department for using "profanity and vulgarity" around the office, supervivors were hopeful that the scandal surrounding the department in recent weeks would begin to fade into memory.

But the firing of Charles J. Cedeno, who grabbed headlines a few weeks ago with allegations of widespread improprieties and mismanagement in the department, has done nothing to cool public speculation.Instead of resolving the questions Cedeno raised, this county that prides itself on clean government appears to have taken the easy way out.

It has acted to silence the bearer of bad tidings without paying much attention to his message.

Two weeks ago, Cedeno publicly charged that the department, which awards about $50 million annually in country contracts, was riffled with bureaucratic problems that virtually guaranteed a loss of taxpayers of millions of dollars every year.

The Venezuelan-born executive charged:

That the county routinely permits cost overruns of up to 10 percent on contracts without official scrutiny.

That at least two county supervisors bypassed proper procedures in buying office equipment.

That $40,000 worth of microfilm equipment was delivered to the Circuit Court clerk's office more than two months before competitive bids were opened.

Since Cedeno was the top purchasing agent and had been highly regarded when the supervisors hired him nearly a year ago, it might be logical to assume that his report of problems would carry some clout.

But the supervisors, who had received complaints in the meantime about Cedeno's behavior in the office, were disinclined to listen to his allegations. Most could hardly contain their skepticism and deprecated Cedeno's criticisms as a "smokescreen" designed to shift public attention away from his own alleged wrongdoings.

It rapidly became clear that Fairfax officials were putting less muscle behind investigating the substance of the charges than they were using to investigate the man who had raised the questions.

The independent auditing firm hired by the county to examine Cedeno's claims turned out to be Peat, Marwick, Mitchel & Co. -- the massive accounting firm which has conducted most of the country's outside audits for more than a decade and which has consistently given the purchasing department a clean bill of health.

That, say some county observers, is like asking a small boy who has been guarding a cookie jar to report on whether it is full.

While no one is questioning the accounting firm's ethics or efficiency, the situation suggests that it may not be in Peat, Marwick's best interest to criticize the procedures of the purchasing department -- the very procedures through which Peat, Marwick has won more than $300,000 in county contracts over the last seven years.

At the very least, it seems unlikely that Peat, Marwick will change its longstanding opinion of the purchasing department on the basis of a two-week audit.

County officials have pointed out that they had asked Commonwealth's Attorney Robert F. Horan to join in examining Cedeno's charges. All well and good, except that Horan has said from the outset he has very limited authority in the matter. Horan can only pursue cases where there may be a violation of state law, and in this case, most of the allegations are covered by county regulations.

That leaves the investigation of Cedno himself, which has drawn much more interest among Massey Building pundits than the charges about the purchasing department.

This week, after interviewing 32 current and former country employes, county officials concluded that Cedeno used excessive vulgarity in the office, applied demeaning and crude nicknames to his subordinates, used offensive obscenities before captive audiences of staff members, openly speculated on the sexual behavior of members of his staff and generally intimidated everyone who worked for him.

The officials agreed that Cedeno is "technically competent" as a purchasing agent. But, they reported, his behavior in the office created an atmosphere of "fear and disgust" that completely negated his professional skills.

Without exception, Cedeno denies every one of the county's allegations. He says he "sometimes curses," but adds that neither his language nor his behavior is offensive.

"If people make this insinuation about the way I hold my pencil," he said, "then they're a bunch of sick people and I don't want to be near them."

County officials insist that the allegations against Cedeno, which led to his firing, are completely unrelated to his allegations about the purchasing department. At the same time, however, they seem to be evaluating the man's charges on the basis of what they believe are his personal habits.

Personal behavior such as that Cedano is charged with is serious business, and if it did occur in this case, certainly cannot be condoned.

But it is equally unacceptable, for the county government to take actions that could preclude a fair and thorough investigation of serious questions about a major county department.

By publicly dismissing Cedeno's charges as a smokescreen and asking an established county auditor to reaudit its own audit, county officials at best are jeopardizing their own, much-prized reputation for clean and open government.

What sensible county employe, having witnessed the current circus in the purchasing arena, will feel secure in blowing the whistle on what they consider to be problems in their own departments?