Web of Silence Surrounding Killing Unravels : The prosecution says Robert Gibson walked his grandmother home, gave her a tranquilizer and then killed her.

It was a crime that “almost slipped through our fingers,” Los Angeles police said--an 84-year-old woman found dead in her Van Nuys home in April, 1983, a kitchen knife protruding from her throat.

There were few clues and no suspects. A ransacked apartment led police to speculate that a burglar had been surprised by Florence Williams and that the intruder wound up killing her. But the evidence “just didn’t add up,” Lt. Al Durrer recalled. Items a burglar usually would have taken were still in the apartment, for instance.

Homicide detectives worked on the case several weeks, then put it on the back burner for 2 1/2 years.

But a tip last month revived the investigation and today Florence Williams’ grandson, 23-year-old Robert Miguel Gibson, a 1985 UCLA graduate, is scheduled to face a preliminary hearing in Van Nuys Municipal Court on a murder charge.

Those most likely to testify against Gibson, police said, are a former girlfriend and members of his family, who allegedly knew that Gibson killed his grandmother but kept it a secret. Police said Gibson’s motive was rooted in Williams’ senility, which continually exasperated the family.

“It’s very difficult to understand the logic, but, from what we can tell, those who knew about it treated the whole matter like it was some evil family disruption rather than a human who lost her life,” Durrer said. “This one almost slipped through our fingers.”

Since Gibson pleaded not guilty Dec. 2, Deputy Dist. Atty. Andrew Diamond said, he has been reviewing taped statements from family members. Police said they have not recommended prosecution of the relatives for concealing information about the crime.

“It’s a very unusual case with many strange twists, and it will all come out eventually,” Diamond said.

Gibson’s attorney, Michael Adelson, refused comment except to say that “we have a viable defense and what it is will come out in court.”

Both sides predicted the preliminary hearing will be delayed until next month, and that the details will not emerge until then.

Homicide Detective Lyle Mayer said Williams was a native of Peru whose family became prominent in Philadelphia and whose son was once foreign minister of Peru.

After she refused to live in a nursing home, Mayer said, Williams was moved to an apartment in the 15200 block of Sherman Way, next door to her daughter, Sandra Gibson, who has since died of cancer, and son-in-law, William Gibson. It was there that she was found dead April 17, 1983, a Sunday, police said.

Suspect Came for Dinner

Mayer said Robert Gibson, the couple’s son, had driven to Van Nuys from his Costa Mesa home earlier in the day to visit his family and have dinner. About dusk, he escorted his grandmother to her apartment where she took a tranquilizer and lay down on her bed, the detective said.

Robert Gibson then left, but returned shortly later, killed her, and “messed up” the home to make it look as though the apartment had been burglarized, Mayer said.

Sandra Gibson found the body about 8:15 p.m. when she took a bowl of soup to her mother, Mayer said.

Florence Williams was in her bed, a blanket pulled up to her chin and the knife sticking out of her throat, police said. The old woman’s cane was bent, as if it had been used to strike someone.

According to Mayer, Williams’ relatives told police at the time that they had no idea who killed the woman.

‘No Clues, Little Evidence’

“It was a perfect murder, no clues, little evidence,” he said.

Police said the unexpected break came Nov. 21, when someone close to the family reported that, shortly after the murder, he had overheard a telephone conversation during which Robert Gibson confessed to the killing. The tipster has not been identified.

“This person told us he couldn’t take it anymore and had to get it out in the open,” Durrer said. “We took it from there.”

Investigators began reinterviewing the family and others. This time, Robert Gibson’s father, sister, and a former girlfriend, who knew him when he was a political science major at UCLA, all said they knew he had killed his grandmother, according to Durrer, who supervises detectives at the Van Nuys police station.

“They apparently thought the right way to go was psychiatric counseling instead of prosecution,” Durrer said, referring to the family members.

Durrer said that Robert Gibson apparently killed his grandmother because her failing health put extreme demands on the family, including trying to prevent William Gibson from carrying out his job as an agricultural engineer, which frequently required him to travel abroad.

The family members, who now live in Inglewood, could not be reached for comment. “The family is obviously very upset that the son was arrested,” defense attorney Adelson said.

Robert Gibson, who police said speaks four languages, was arrested without incident Nov. 26.