It started out like just another kidnap case in a country where kidnapings and murders are routine affairs. But the beleaguered government of El Salvador is using the recent arrest of Guillermo Antonio Roeder Escobar as additional proof to its U.S. backers that it is cracking down on abuses of human rights.

Roeder, as it turns out, is no ordinary Salvadoran thug but rather a well-connected former major in the Army National Guard and the first high-ranking former officer to be arrested for any major crime. As such, he could provide a handy example of the "renegade ex-military men" on whom the government has tried to pin most of the violence carried out against civilians here.

More than just a "renegade," Roeder in recent years has operated his own private army, according to police. He rented his "troops" as security guards to protect the same kind of rich, fearful Salvadorans whom police now allege he kidnaped. His conviction thus would delight the wealthy families who were his victims and who continue to wield enormous power here, especially with the newspapers that detest the current government.

Roeder's conviction also would not overly offend the Army, which expelled him two years ago for his alleged role in a multimillion-dollar fraud. And unlike the case of the murdered American churchwomen, which required U.S. aid and considerable prodding to resolve, the Roeder case has been entirely a local initiative.

But there is one very delicate problem: Roeder's case may lead more places than the government cares to go.

It could lead, for example, to some highly placed politicians or military officers, for Roeder's operation was of a size and type that would seem to have needed influential protection. Such a link could be wildly explosive on a divided government that is trying to exert leverage on a divided military in a war-torn country one month from a crucial election.

Roeder was arrested for kidnaping and extortion along with five others Jan. 28 as the result of an anonymous tip, according to Capt. Ricardo Trigueros, chief of investigations of the National Police. Under the Salvadoran criminal justice system, the six have been jailed pending formal charges.

The police said Roeder had at least 100 armed men under his personal control. Some accounts put the number at 400 and said most of them were kicked out of the armed forces for assorted common crimes.

The police statement at the time said Roeder was arrested at his apartment while awaiting delivery of $700,000 in ransom for Guillermo Bustamante Augspurg, a businessman whom some members of the gang had held hostage for 49 days.

The story had everything. Police called Roeder "the intellectual director of a kind of mafia dedicated to acts of blackmail, extortion and other crimes." One of two women arrested was his lover and the other had served as the gang's telephone contact with relatives of the victims, according to police. Her estranged husband had been beaten to death in a 1980 murder that was never solved.

This widow allegedly had performed the actual kidnaping of Bustamante, dragging him into a stolen red van as he left a barbershop around noon Dec. 9. The kidnapers told the family it would cost $4 million to save Bustamante's ears.

Roeder befriended the family and urged them to pay the ransom to protect his dear friend Bustamante, according to the police account. When police broke into his office, they said, they found an arsenal of weapons, disguises, tape-recording equipment and ammunition. Police said the cache was enough to lead them to conclude that Roeder had operated either one of the local rightist death squads that plague this city or "one of the clandestine subversive organizations" of the leftist guerrillas.

That was early in the case, when the headlines were splashy. Now officials are being more cautious, saying only that they are investigating. "So far there's no evidence tying these people to terrorists," said Trigueros. "It seems they were only taking advantage of the problems of our country to make themselves rich."

Rich they were. Police said Roeder's group collected at least $800,000 and probably more from the family of Roberto Siman, another businessman kidnaped and released in 1980. Most of that went to buy an apartment and a yacht in Miami and tickets back and forth for Roeder and his friends, police charged. Roeder was said to have had a ticket to Miami when he was arrested.

The city is now awash in reports that the probe has tied Roeder to half a dozen other lucrative kidnapings.

In an interview, El Salvador's defense minister, Gen. Jose Guillermo Garcia, widely considered the power behind the government here, would not discuss details of the probe but promised that the government would pursue the Roeder case wherever it leads.

"It demonstrates our neutrality, that all are equal and that we will act against anyone, whatever his connection," Garcia said, holding his arms wide.

That could prove to be a wide net indeed. Letters Roeder has written from jail, quoted in the newspapers, find him remarkably complacent and relaxed, confident that his money, his friends and his lawyers will gain his quick release. The widow in his group told reporters that Roeder made a lot of visits to the Treasury Police, an armed forces branch that is widely feared for its lawless reputation.

Observers are also quick to add that one of the current leading candidates for president March 28 is another former National Guard major, Roberto D'Aubuisson, an extreme right-wing militarist. No link has been established between the candidate and his former National Guard colleague.

At the moment, the case remains a pleasing one indeed to the party in power, the Christian Democrats, who want to appear to be curbing the military.

"The case gives the Army a new and more honest face to the people," said Adolfo Rey Prendes, the party's leading candidate for the legislature. "For the first time an officer has been jailed. Perhaps people will start thinking things really have changed."