(CBS) — Authorities are looking for the person who drowned nearly a complete a litter of coyote pups in the northwest suburbs. One of the animals is recovering from serious injuries.

Weighing less than a pound, too weak to open its eyes, barely breathing — this was the condition of the four-week-old coyote pup when it was found clinging to life May 11.

“This is clearly an act of destruction,” Chris Anchor, chief wildlife biologist for the Forest Preserve District of Cook County, tells CBS 2’s Dorothy Tucker.

The heinous act took place at Penny Road Pond in Barrington Hills.

A witness called 9-1-1 to report seeing someone throw a bag into the pond. Six coyote pups were found dead, but one was still alive.

Dawn Heller of the Flint Creek Wildlife Rehabilitation that treated the pup points to the X-ray of its shattered leg as evidence of the abuse it suffered. She suspects the animal was beaten with a bat or swung around by the leg.

Authorities can only speculate on a motive. They say perhaps the person felt threatened by the pups’ mother. But the vast majority of coyotes present no problems for humans.

Anyone with information is asked to call police.

The person who killed the animals could face felony charges.

The surviving coyote pup is doing better, but veterinarians aren’t sure its leg can be saved. If the coyote does not heal completely, it will have to spend the rest of its life at an animal sanctuary, rather than the wild.