Ira Attebury, a quiet man whose deadly barrage of shotgun and rifle fire killed two people and wounded 31 others at San Antonio's annual Fiesta celebration, seemed to spend most of his time behind the drawn curtains of his motor home.

On the infrequent occasions when he talked to managers of trailer parks here, he complained variously about banks, about persecution by police and about unfair treatment by physicians at the Veterans Administration hospital.

When messages were brought to his door, he refused to answer the knock, but communicated from behind a curtained window.

Behind those curtains was an arsenal of weapons.

It was the motor home that served as his fortress when he suddenly opened fire with a shotgun on police officers at the starting point for the gala Battle of Flowers parade Friday afternoon.

When police were able to enter the vehicle 75 minutes later. they found Attebury dead from a pistol shot to his head. Nearby were eight rifles, three shotguns, four pistols and hundreds of rounds of ammunition.

The rifles ranged from light weapons to a high-power Savage 300, termed "an elephant gun" by police.

After firing first with a 12 gauge shotgun, Attebury had turned to a Colt AR15 semi-automatic rifle which was found jammed with one live round remaining in it.

Two women parade spectators who were killed were found by the Bexar County medical examiner to have been struck by bullets from his rifle.

The shot that killed Attebury, despite the heavy fire on the trailer from police, came from his own.38-caliber Smith and Wesson special. police said.

Authorities are still trying to piece together Attebury's background.

Members of his family in Missouri said the 64-year-old man had grown up on a farm near the town of Naylor in the southeastern part of the state.

After service in the Coast Guard during World War II, he had been an independent trucker. He told trailer park managers here that he was receiving disability pension payments.

It appears that Attebury had lived in San Antonio for more than a year, but little has been learned about the period before April 1978, when he appeared at a local trailer park.

Clayton Richards, park operator, recalled that Attebury had hallucinations about one thing or another, and... I notified him I wanted my lot back."

Richards said Attebury had complained that a grant trailer had parked next to him overnight "and they were watching me."

"One day he would be telling me he wanted the police to help... and the next day he would say the police were after him." Richards said.

Attebury next appeared at a trailer park at the opposite end of the city on Nov. 1.

There, too, he mentioned difficulties with police, though did not say in what city. He complained that an officer had stopped him and asked him for money and that other officers made abusive gestures toward him, according to the manager.

The manager said that Attebury had told her he was planning to leave this weekend after the parade, but at 5:30 p.m. Thursday she discovered he had left.

He apparently had driven directly to a parking space at a tire store at the intersection where the parade was about to start, and spent the night there.

Mrs. John Canty, parade chairman. said she standing at the intersection talking to a police inspector just before the event was to start. Nearby before the event was to start. Nearby were two police lieutenants.

All three were seriously wounded by Attebury's first shotgun blasts.Mrs. Canty was not hit. In all, seven policemen were wounded.

The parade was canceled for the first time in its 89-year history.

Why did it happen?

Said one officer: "All you can say is that he didn't like policemen." CAPTION: Picture, Ira Attebury, identified as sniper who killed two persons in San Antonio, in early 1960s family photograph., AP