Talk of Drugs Follows 4 Slayings : Crime: Neighbors say Robert Marks had 6 locks on his door and lots of visitors. Tuesday night, he and 3 other men were shot to death.

The neighbors were never quite sure what to make of the comings and goings at the little one-bedroom garage apartment on South Burnside Avenue in the Mid-Wilshire District. The place had been occupied for decades by Robert Marks, a 59-year-old retiree who lately seemed to entertain a succession of young men.

While their neighborhood of neat stucco duplexes and single-family homes was certainly not crime-free, they wondered why Marks had installed six locks, four of them deadbolts, on his two front doors. They wondered, too, about the loud arguments that would escape from the apartment late into the night. Drugs, they figured.

On Wednesday, the neighbors had more to wonder about. Marks and three of his friends had been found shot to death the night before inside his apartment--victims of what police called “execution-style” murders.

While detectives listed the motive as robbery, they had no suspects in the quadruple slaying. They were still interviewing witnesses Wednesday--gathering evidence and trying to determine what, if any, weight to give to the neighborhood theory that drugs were involved.

“What relationship they have to this multiple homicide, we just don’t know,” said Los Angeles Police Detective Dan Andrews. “I think robbery was the motive. Now if we’re talking about robbery for drugs and/or robbery for money, I don’t know.”

Though statistics were not available, Andrews described quadruple murders as “highly unusual.” The killings frightened and upset residents on the 1200 block of South Burnside, where neighbors have known one another, and Marks, for years, and had often discussed among themselves their suspicions about the retired tavern owner.

“It’s not like . . . this sort of thing happens all the time,” said Gretchen Goldsmith, a graduate journalism student at USC. “This is a very family-oriented neighborhood. There are a lot of children on this street. This is very shocking.”

Despite the problems Marks caused the neighborhood, he had made friends there. One woman remembered him Wednesday as “a high-class fellow, a real nice guy” and said she could not imagine anyone killing him.

“I just don’t understand how this happened, who would do this and why this would happen,” said the woman who, like many neighbors, did not want her name published because the killers were still at large. She shook her head. “It’s terrible,” she said. “It’s terrible.”

Police identified the other victims as William Terry, 27, of Los Angeles; Celedinio Ligtas, 33, of Los Angeles, and Gene McCullars, 28, who neighbors said had been rooming with Marks for about six months. Police said Terry and Ligtas were visitors to the apartment.

The men had gathered at Marks’ apartment sometime between 5 and 6:30 p.m. Tuesday to watch the fourth game of the National Basketball Assn. championship series on television. When a fifth man showed up about 6:30 p.m., police said, he discovered two bodies, ran back out the door and told a neighbor to call for help.

The neighbor, who was afraid to be identified, said she went into the apartment and spotted “Gene (McCullars) laying face down in a pool of blood and Bob (Marks) laying in the opposite direction. Gene was half in the hall, going into the bedroom” and Marks was in the bedroom, she said. She did not see the other two men.

Andrews said all the victims were casually dressed. All were found on the floor in the bedroom; it is possible, he said, that they had been ordered there by their assailants. All had wounds in their torsos, although he would not say if they had been shot in the chest or the back.

No weapons or bullet casings were found.

Andrews said it appears that the killer or killers knew Marks or the other men; there was no sign of forced entry into the apartment, which had been ransacked. He also said police found no drugs or drug paraphernalia.

Neighbors, however, were convinced that Marks’ friends--if not Marks himself--were either using or dealing drugs.

The constant traffic in and out of apartment 1242 had been the topic of their most recent Neighborhood Watch meeting, the neighbors said.

“There’s been problems back there,” said the woman who discovered the two bodies, “and we’ve had to call the police before. But basically (Marks) himself hasn’t been a problem.”

Another woman Said she held a garage sale last weekend and McCullars showed up “either drunk or on drugs.” His pants were unzipped and he appeared “real spacey-looking.”

According to this woman, Marks had lived in the neighborhood since at least 1964. He used to own a bar on Venice Boulevard, but he retired several years ago when he broke his hip.

About six months ago, she said, Marks’ apartment was burglarized and ransacked. Frightened, he moved into a nearby motel for two or three weeks. When he returned, he asked McCullars to move in with him. It was then, she said, that he installed the locks.