SAN FRANCISCO — A Northern California woman is accused in the brutal beating of a puppy that shocked even veteran law enforcement officials, a sheriff's spokesman said Wednesday.

Janice Aguilar, 39, was arrested Wednesday on suspicion of animal cruelty and death. Authorities say she beat the dog, put the injured animal into her backpack and walked away instead of seeking treatment from a veterinarian, Madera County sheriff's spokeswoman Erica Stuart said.

Aguilar told deputies that the dog was attacked by a pit bull.

Her neighbors in the Sierra Nevada foothills town of Oakhurst called deputies Wednesday afternoon when they saw her beating the dog and banging it on the ground, Stuart said.

She said that before deputies arrived, Aguilar put the injured dog — described by Stuart as "crying in pain" — into her backpack and flagged down a passing car.

"The sick part of this, the witness could hear the dog whimpering, and assumed the woman wanted go to a vet," Stuart said.

The driver drove Aguilar and the dog to the offices of two separate veterinarians, but Aguilar refused to take the puppy for treatment, said Stuart.

"Instead, she got dropped off near a park," Stuart said.

The dog, believed to be a Lab mix between 8 and 11 weeks old, was put down by another witness who saw the severe pain it was in and thought it was beyond help, Stuart said.

"The witness felt the only thing to do was to put the animal out of its misery," Stuart said.

"I have dealt with animal neglect, but I have never dealt with such an extreme case of cruelty to an animal," Stuart said.

Bail information, if any, and a court appearance date for Aguilar was not available.