The parole-selling scandal that has rocked the final days of Gov. Ray Blanton's administration here appears to have significance beyond the borders of Tennessee.

For the problems encountered in the lengthy inquiry, and the techniques and statutes used, illustrate an increasing federal role in policing state and local corruption.

A review of the Tennessee investigation shows what federal authorities encounter in similiar cases acrosss the nation: charges that the inquiry is politically motivated, sensitivity to entering local cases, the chance of friction between aggressive investigators and prosecutors, and the development of sophisticated investigative tools.

The long-smoldering Tennessee investigation burst into the open last month when the FBI arrested three Blanton aides on extortion and racketeering charges in connection with an alleged scheme to sell legal papers freeing state prisoners.

T. Edward Sisk, the governor's legal counsel, Charles Benson, his extradition officer, and Charles Frederick Taylor, a veteran state trooper assigned to Blanton's security force, allegedly were caught with marked $100 bills delivered by an FBI informant.

Blanton has denied any knowledge of wrongdoing by his aides. Federal sources say there is no hard evidence yet that the governor was directly involved in the payoffs, though his name was mentioned in secret tape recordings made of the alleged plotters.

The governor testified recently before a federal grand jury still probing the extent of the scandal. No one here has yet labeled the case "prisongate," but Blanton has hired former Watergate prosecutor Janes F. Neal as his attorney. And political opponents gleefully have taken the Democratic governor to court, where a judge ruled that his practice of delegating pardon authority to aides was illegal.

To Blanton, the timing of the arrests -- just a month before he leaves office after declining to run for reelection -- is proof of a continuing FBI vendetta against his administration. "He hates the FBI," press secretary Jim Gilchrist said the other day.

Officials familiar with the case privately have expressed amazement at the brazen behavior of the accused, and at Blanton's failure to heed early warnings of the impending scandal.

The federal inquiry has been known publicly since Sisk's records were subpoenaed more than two years ago. In mid-1977, Benson, another of those arrested, was indicted on a related state charge -- tampering with an extradition proceeding.

And just this past summer, Marie Ragghianti, whom Blanton had fired as chairman of the state's Pardon and Parole Board, gave public testimony about suspected payoffs in a court fight to win her job back.

Gilchrist acknowledged that, in hindsight, it appears the governor may have been too loyal to his aides. But the spokesman said, "He stands behind his people."

According to FBI affidavits filed in the case, Trooper Taylor was a bagman who bragged incessantly -- and unknowingly -- to a hidden videotape recorder about his past and current exploits in freeing convicted felons.

He offered money-back guarantees, he reporterdly said, and would deal for anyone who hadn't assaulted a "minor child." He allegedly said he was working on at least a dozen other sentence reductions that would be announced in the last week of Blanton's term "so it would just be reported on once."

The Tennessee story is being repeated increasingly across the nation as the FBI and Justice Department step up their efforts to meet the Carter administration's priority of prosecuting public corruption.

Six months ago FBI Director William H. Webster announced that more than 500 officials -- from local sewer board members to U.S. senators -- were under investigation. The latest figure is near 900.

The Justice Department's public integrity section now has grown to about 25 attorneys who coordinate such prosecutions and travel widely to try some cases.

In the past few weeks, for instance, there have been convictions of the assistant police chief in Houston, a fund-raiser for Gov. Milton Shapp in Pennsylvania, a powerful state senator in Mississippi, and an insurance commissioner in Florida, according to Thomas H. Henderson, who heads the section.

Increasingly, too, as in the Tennessee case, the prosecutors are using a racketeering statute which was aimed originally at organized crime figures. It carries a 20-year penalty upon conviction and lets the government seize the assets of racketter-controlled enterprises.

"It's probably the most powerful criminal statute we have to work with," Joe Henehan, chief of the FBI's white-collar crime section, said in a recent interview.

Blanton's aides were arrested after a break in a long-stymied case. Taylor allegedly met with the FBI informant -- reportedly a Memphis topless club operator with a criminal record -- on several occasions in motel rooms monitored by videotape cameras and FBI agents.

After one such visit to Memphis in October where Taylor was allegedly filmed counting out $2,000 in marked bills, an FBI agent -- posing as the informant's driver -- drove him to the airport. Another agent took the same flight back to Nashville, and other agents watched Benson meet him in Sisk's state car.

During the taped meetings, Taylor frankly discussed the problems he faced in his work. Among the revelations in FBI arrest affidavits:

He recalled warning another customer who had reneged on a payment, "These people I'm fronting for have a product to sell. I don't give a f -- if you want to play. This is the only game in town."

He cautioned against telling the lucky prisoner too much, recounting how one young man told the parole board he was expecting favorable treatment because "his daddy told [him] he had everything worked out."

He complained about the likely new corrections commissioner under incoming Republican Gov. Lamar Alexander, saying "a man'll have to do his time if he [Alexander] gets in there."

Hints of alleged corruption in the granting of pardons and paroles in Tennessee have been around for years. One veteran law enforcement official here scoffed at the shock and surprise with which some officials greeted the arrests.

"Back in the '50s, the word was you could get anyone out for $3,500. Now it's up to 15 [$15,000] -- that's inflation for you."

Lawyers and officials around town can quickly cite cases in past administrations where attorney friends of parole board members made sudden and impressive strides in improving their net worth.

Thomas Shriver, the local state prosecutor, heard charges nearly four years ago that Sisk was receiving money to arrange prison releases. But Sisk had a good reputation and the matter was not pursued then by the state.

"Sometimes because of local political considerations, it's easier for us to come into such cases," a Justice Department prosecutor said.

Charles Hill Anderson, the Republican U.S. attorney, did start an investigation of parole-selling allegations in mid-1976 and Sisk's records on prisoner releases were seized that October. Blanton immediately began charging that the probe was politically motivated. In early 1977, he went to U.S. Attorney General Griffin B. Bell with his complaint, with no apparent effect.

Anderson turned the investigation over to public integrity section attorneys from Washington to put the political charges to rest. His successor, Hal Harden, a Democrat whom Balanton had appointed to a judgeship, also excused himself from the case for appearances' sake.

At one point last year, Blanton ordered a state investigation of the charges but said it cleared Benson shortly before he was indicted by a local grand jury. State prosecutor Shriver publicly labeled Blanton's injury as a whitewash. The governor did not remove Benson from his job, although he was handling prisoner release papers even after the indictment.

About the same time, Blanton Fired Ragghiant, who had been cooperating with the federal grand jury probe.

But the volatile situation seemed to fizzle out early this year when the federal grand jury expired without returning any indictments. Sources said the Justice Department refused to approve proposed indictments being pushed by the FBI because the evidence wasn't strong enough.

It wasn't until last summer, according to affidavits filed in the case, that the persistent FBI agents got their break.

Though the parole-selling investigation has been simmering for more than two years, more public contention here has been focused on Blanton's controversial promise last year to commute the sentence of a convicted double murderer who is the son of one of his former patronage officials.

The other night a singer at a local night spot recalled that case in a tune entitled "Pardon Me, Mr. Blanton." The performer also noted the governor's year-old practce of refusing to answer "negative questions" from the press. "I wonder if that will work at the grand jury," the singer said.