Woman’s Slaying Puzzles Relatives : Violence: The 77-year-old victim was extremely cautious, granddaughter says. Police say burglar may be responsible for the killing in Van Nuys.

The brutal killing of an elderly woman in her Van Nuys home has baffled relatives and friends, who described her Monday as a habitually cautious and private person who would never have opened her door to a stranger.

“Either you had a key to my grandmother’s house or you didn’t come in,” said Monine Horn, one of the three grandchildren of Berneda McMackin, 77, whose body was discovered Sunday afternoon by police and neighbors in her closed, burning house.

“Someone had gone in and stabbed her, beat her and then tried to set her on fire to try and hide the crime,” Detective Stephen Fisk said.

No suspects have been arrested in the slaying, which police say may have been committed during a burglary.

News of McMackin’s killing left her family distraught and angry and nearby residents on Blewett Avenue frightened.

“It’s scary,” said one neighbor who asked not to be identified. “You hear about things like this happening at other places.”

“I was shocked,” said another neighbor. “She never bothered anyone.”

Reed, whose husband accompanied police into the burning house to find the body, said the front and rear doors were closed but unlocked, which relatives said was unusual.

Horn said it was unthinkable that her grandmother, who had lived alone in the house since the 1976 death of her husband, a former Los Angeles County sheriff’s deputy, would open her door to a stranger.

McMackin’s daughter, Robin Crays of Las Vegas, said detectives showed her a mason’s tool resembling a putty knife, which they believe was the murder weapon, and said the contents of her purse had been dumped on the floor, indicating that robbery may have been the motive. She could not tell whether anything had been taken.

“We don’t understand how this person got in,” Horn said.

Neighbors agreed.

“As close as we were, I had only been inside her house once in 40 years,” said an elderly woman for whom McMackin used to shop. The woman said McMackin would stop by her house every few days to chat about their families.

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Margaret Reed, another neighbor, said that after the Northridge earthquake, McMackin would not even let Reed’s husband, who works for the Gas Co., into her home to make sure her gas was shut off.

“She wouldn’t even open the door to him,” Reed said. “So I can’t believe she’d open the door to just anybody.”

Neighbors also said one of McMackin’s two dogs was extremely protective of her.

McMackin was found by Reed’s husband and police in the doorway of her smoke-filled kitchen after residents smelled smoke coming from her home about 2:45 p.m. Firefighters extinguished the blaze within a couple hours.

Her husband said both doors to the house were still closed, Reed said.

Crays said that she had talked to her mother on the phone between 11:30 a.m. and noon on the day of the killing and that “she was fine” and was waiting for a phone call from Horn, who was possibly going to stop by for a visit.

“She was a great mother,” Crays said.

Born in Nebraska, McMackin had lived in the modest house on Blewett Avenue since 1949, family members said.

Times staff writer Chip Johnson contributed to this story.