Early in the morning, she used a walking stick attempting to save the 92-year-old from a teenager who then turned on her.

A young man was identified on Friday as the suspect in the sexual assault and beating to death of an 86-year-old California woman remembered as a hero by investigators and neighbours after she used a walking stick to try to stop an attack on her friend.

Neven Glen Butler (18) was arrested the same day he was detained in an unrelated assault of a 92-year-old woman a few miles (kilometres) away, Sacramento sheriff’s Sgt. Tony Turnbull said. She was treated at a hospital for facial injuries.

“I think she’s a hero. She gave her life to save her friend,” said Dolores Hines, who lives down the block from Fusako Petrus and her walking companion, whom authorities have not identified.

The friend was the initial target of the early morning sexual assault on the running track of Highlands High School in the North Highlands suburb of Sacramento, Mr. Turnbull said.

Petrus was killed after she came back to help, hitting the attacker with what he described as “a small walking stick” to try to fend off the man.

“She died trying to help her friend,” Mr. Turnbull said.

Very intricate case

“The case is certainly a lot more complicated than it appears,” high-profile defence attorney Linda Parisi said. “There’s a lot more to find out about this young man and just the whole set of circumstances.”

Butler played football in 2015 at the same high school where Petrus died, said Twin Rivers Unified School District spokeswoman Zenobia Gerald. He also was on the football roster for the 2016 season and was on the track and field roster, she said, though she could not immediately say if he participated in the sports.

Butler was known as a class clown who didn’t take his studies seriously, Robert Hills told The Sacramento Bee. He said he has known Butler since the fourth grade and kept in touch after his friend moved to a different high school.

A makeshift shrine with candles and flowers was erected on the driveway and tucked into the chain link fence of Petrus’ neatly manicured one-story yellow home with meticulously trimmed shrubs. Neighbours said they were not surprised Petrus tried to stop the assault.

Helping nature

“It sounds like something she’d probably do. She’d help anybody,” said Don Brown, who lives across the street.

Neighbour Lloyd Miller said Petrus met her husband in her native Japan after World War II. She was a clerk at the store of California’s former McClellan Air Force Base until her retirement, he said.

“She walked every day but Saturdays,” said Mr. Miller (88), who usually watched her leave while eating breakfast by his front window. “I’d always say, ‘Be safe, Fusako’ to myself.”

Don Hines, Ms. Dolores Hines’ husband, remembered Petrus teaching his family how to make candied persimmons from the fruit growing on a neighbourhood tree.

“I don’t know anybody who would not love her and appreciate her,” he said, choking back tears.

Butler, the suspect, is being held without bail on suspicion of murder. He is scheduled to make his first court appearance on Monday.

Ms. Dolores Hines said Petrus’ friend suffered a swollen lip and scratches and bruises from her neck to her chest where the attacker tried to strip off her clothing.

Murderous assault

The friend told Ms. Hines that she was running to get help when she looked back to see the attacker kick the tiny Petrus in her head.

“She’d been doing the walk for 40 years,” recalled Dolores Hines, clutching a box of tissues to her chest.

Petrus felt safe in the neighbourhood, Ms. Hines said, recalling what she told people who worried about her- “’I’ve got a friend who goes with me. And I’ve got a stick.’”