Two federal crackdowns on public corruption - each the biggest US probe ever of its kind - have spurred reforms aimed at reducing further abuse. In the first of these crackdowns, federal convictions continue to pile up from investigations into highway bid-rigging in more than a dozen states. More than 185 people and 165 corporations have been found guilty. The second involves a probe of massive corruption among state commissioners in Oklahoma. More than 200 commissioners have been found guilty in an old system of kickbacks from suppliers that began unraveling during an Internal Revenue Service investigation.
In the wake of these investigations, some states have turned to computers to spot bid-rigging patterns. And Oklahoma has adopted laws to tighten spending by its commissioners.
Now, however, a third major form of public corruption appears to be increasing: law enforcement officials accepting a slice of the billions of dollars of illegal drug money swirling through a largely unchecked, underground distribution system.
Drug money corrupting law enforcement officials is ''a serious problem becoming more serious,'' Ray Vinsik, special agent in charge of the Southeastern region for the Drug Enforcement Administration (DEA), said in an interview.
Neither the Federal Bureau of Investigation nor the DEA has been keeping a separate count of the arrest or conviction of law enforcement officials, their spokesmen say. But agent Vinsik cites these drug-related indictments within the last two years in Georgia alone (most have led to convictions, a DEA spokesman here says): nine state police officers, six deputy sheriffs, six sheriffs, two police chiefs, two deputy prison wardens, one warden, and an agent for the Georgia Bureau of Investigation.
Catching corrupt law enforcement officials is no easy task, especially if the officer tries to get his colleagues to look the other way in return for past favors.
But some of the nation's police chiefs and federal agents (DEA and FBI), gathered here recently to examine how to fight corruption in their own ranks, offered these strategies:
* Look for signs of officers living beyond their means.
* Rotate people off narcotics and vice assignments; be suspicious of officers who do not want to be moved from such tasks.
* Put ethical job requirements into writing.
* Prosecute vigorously cases of detected corruption. (One chief said some prosecutors do not welcome police-corruption cases, saying they have to get along with the police on other cases.)
* For investigators, choose the officers the least likely to be tempted by the extremely large drug (and other) payoffs available to corrupt officers.
Since the FBI has become more directly involved in drug cases, ''we've become more aware of police corruption involving drugs,'' says William Clancy, unit chief for public corruption and labor relations.
Illegal drug money is having ''a rather substantial impact'' in corrupting some public officials, he says. But FBI agents are ''getting better'' at detecting this kind of corruption as they become more familiar with their added responsibilities, he says. However, most FBI offices and US attorneys' offices (which prosecute the cases) are ''understaffed'' compared to the massive size of the problem, he adds.
And a change is occurring in the way such drug-related corruption takes place. The drug dealer may no longer be a complete stranger to the officer, DEA official Vinsik says. ''He may be a banker, a lawyer, a next door neighbor . . . anyone.''
At a time when the DEA estimates illicit drug profits exceed $80 billion a year and only a fraction of the drugs is seized, there is ''corruption at a very high level,'' says Vinsik.
But there are some signs that may indicate progress.
Federal indictments of public officials (federal, state, and local) have shown a fairly steady increase over the past several years, from 557 in 1978 to 879 in 1981. The number dipped slightly to 729 in 1982, says the Justice Department. A spokesman was unable to identify which were drug-related.
Federal convictions of public officials totaled about 300 in 1982, says the FBI's Mr. Clancy.
But regarding public corruption, FBI official John Glover, assistant director of the FBI's inspection division, says: ''We're looking at it more closely than we ever had before. We're getting better at it.''
One of the most recent federal convictions was of an individual who had been working as the ''principal break-in guy'' for the FBI, according to an FBI official. He was sentenced to prison in mid-May for transporting stolen diamonds , tax evasion, and other offenses.
But convictions of DEA or FBI officials are rare, say officials in both agencies.