UPDATE : Sudden Surplus of Suspects Marks Case of Slain Monks : Arizona officials seek links between 2 apparently unconnected sets of possible killers. Temple security has been increased.

Their shoes left at the doorway in the Buddhist custom, three women sat on the floor of the Wat Promkunaram Temple and chatted as they rubbed polish into brass candlesticks.

Nearby, a visiting monk in a saffron robe perched stoically on a hard bench, oblivious to the conversation and the lively Thai music in the background.

Don’t bother him, the women warned. He’s meditating.

Temple members have grown protective of their monks in the months since six were executed in their living quarters along with a Buddhist nun and two young students. The positions of their bodies suggested that they were kneeling side by side when each was shot in the back of the head.

As the congregation prepared last week for a ceremony commemorating the 100th day since the deaths, local authorities struggled to sort out a muddled criminal case that has emerged from the worst mass killing in the region’s history. Two sets of apparently unconnected suspects have been charged with the murders and are awaiting trial.

For the small Buddhist community, largely immigrants from Thailand and Cambodia, the arrests have brought a sense of relief. Early fears that the killings were hate crimes have now been allayed.

But for the local sheriff and the county prosecutor, the case has become a career-threatening minefield.

From the first hours after the bodies were discovered on Aug. 10, Maricopa County Sheriff Tom Agnos promised that the killers would be brought to justice. Deputies worked around the clock combing every inch of the temple and its ransacked living quarters. A hastily formed task force followed hundreds of leads, nearly all of them futile.

A month passed and investigators had no clear suspects and little to tell the public. Then, on Sept. 10, a man who called himself “John” telephoned to say that he had met someone in a Tucson park who claimed to have participated in the murders. The man was overwhelmed with guilt, John said, and had to check into a psychiatric hospital.

Within hours, investigators found the man at the Tucson Psychiatric Institute and rushed him back to Phoenix for questioning. His name was Mychael Lawrence McGraw, police learned, and there was no “John.” McGraw had phoned police himself from the mental hospital.

Nevertheless, investigators listened to his story of traveling to Phoenix with some friends and waiting outside the temple as six or seven of the group robbed and killed the monks.

Investigators quickly picked up four of the men McGraw named. After lengthy interrogation sessions, three made confessions and, along with McGraw, were charged with murder. They are Dante Parker, 20, Leo Valdez Bruce, 28, and Mark Nunez, 19.

But the case quickly began to unravel. The men recanted their confessions after they got lawyers. Phoenix newspapers quoted acquaintances of McGraw as saying that he is a habitual liar. And an investigator acknowledged in court that a number of key details in one suspect’s confession had been supplied to him by a deputy early in the interrogation.

Meanwhile, an even tougher problem was emerging. On Oct. 23, nearly six weeks after McGraw and the others were arrested, the state crime laboratory identified a .22-caliber rifle belonging to a 17-year-old who lived at Luke Air Force Base as one of the murder weapons.

The youth and a 17-year-old friend were driving on the base 10 days after the murders when they were stopped by military police, who then spotted a rifle in the car. The next day, a Maricopa County sheriff’s deputy sent the rifle to the state lab for a routine, low-priority analysis.

When the unexpected results came back six weeks later, detectives quickly picked up the boys and a 16-year-old friend. Investigators learned that the younger brother of one of the teen-agers had lived with the monks only a few months earlier. All three had visited the temple and heard rumors that the monks kept large sums of money. Two of the youths are being held on murder complaints. One of the 17-year-olds and a fourth juvenile were named as suspects in court documents, but they have not been charged.

Prosecutors are pressing ahead with the cases against both sets of suspects, even though they have not yet found any indication of a connection between them.

The results of a public opinion poll to be released this week show that both Agnos and Maricopa County Atty. Richard M. Romley have been significantly damaged by their handling of the case, said Earl de Berge of the Behavior Research Center in Phoenix. “There is a very substantial erosion in public confidence,” he said.

At the temple in the cotton fields west of Phoenix, life has changed irrevocably. Doors that went unlocked are now wired into a high-tech alarm system. A wrought-iron fence and gate have been installed, and volunteers have washed away fingerprint smudges and blood and brushed on a fresh coat of paint.

And the search goes on for monks willing to replace the six who were killed--the temple’s full contingent.