LOS ANGELES -- Her martial arts skills may not be quite what they once were, but still, you don't mess with Lady Ninja.

Authorities say that's a lesson a California man learned painfully after he began shoving around an 82-year-old woman at a Fontana apartment building.

The woman's 67-year-old friend, Lorenza Marrujo, jumped into the fray and with a swift kick here, a finger-bending manoeuvr there and a couple of solid elbow smashes to the sternum it was all over. Police arrived to find him on the floor with one of Marrujo's knees on his neck and the other on his chest.

Marrujo, who likes to be called "Lady Ninja" and has a black belt in jiu-jitsu, said she was in her third-floor apartment Monday when she heard screams coming from a neighbour's first-floor unit and went to investigate.

There, she said, she found a man attacking her 82-year-old friend, Elizabeth McCray.

Marrujo, who stands only 4-foot-10 and weighs about 100 pounds, didn't hesitate to mix it up with the younger, 5-foot-9-inch, 170-pound assailant.

"I took him down with one sweep kick under the back of his legs," Marrujo told The Associated Press on Thursday. "Then I elbowed him in the sternum and he went, `ugh, ugh' because it really hurt."

He was screaming in pain and pleading with her to stop bending his fingers back when she finally pinned him to the floor and told him to "chill out."

San Bernardino County jail records show Donald Robert Prestwood, 59, was in jail Thursday for investigation of felony elder abuse. Fontana police Officer Jennie Venzor said authorities are continuing to investigate, and it's possible he could face additional charges.

No court date was immediately scheduled, and it wasn't immediately known if Prestwood had retained an attorney.

Shortly before the attack, Marrujo said, Prestwood, who once lived in the same apartment building, had shown up at her place appearing intoxicated and saying he was looking for his girlfriend. She said she chased him away with a baseball bat.

When she went to aid her friend, she found he was choking her and beating her with a cane.

"I slapped him around a little because I was really angry," she said of the beating she gave him.

Marrujo, who once worked as a security guard, said she began studying martial arts nearly 40 years ago for personal protection. Still, she complained after the attack that she wasn't as sharp in battle as she could have been.

"I'm getting rusty, and I don't need to be rusty," she said, adding she is going to step up her workouts to be better prepared next time.

McCray was impressed though.

"I don't how she took care of him, but she was like boom boom boom," she said Thursday as she recovered from her bumps and bruises.

Police were impressed too, although they warned that in many instances it's much safer to call them and let the professionals handle things.

"But in this case it worked out, and she saved her friend's life," Venzor told The Associated Press.

"She's tiny, she's like 4-feet-10, maybe 100 pounds," the officer noted.

"But," Venzor added with a chuckle, "she's strong."