The gruesome discovery of an apparently slain dog on a California beach this week has stoked a social media outcry and demands that the killer be brought to justice.

A team of Hawaiian canoe paddlers found the dog after first seeing a shovel standing upright in waist deep water off Marina del Rey. On closer inspection, the blade of the shovel was driven into the ocean floor, and the handle rose up through the dog's collar.

"It appeared that someone used the shovel to force the dog under water and drown it," said reporter Malia Zimmerman, a member of the 6-person canoe team.

Zimmerman's Facebook post showing the dog stretched out on the beach drew widespread concern even as the Los Angeles County Department of Animal Care and Control on Thursday launched a criminal investigation into animal cruelty.

The dog’s Los Angeles County animal license was still attached to the dog’s collar. It appeared to be a mixed breed.

The license was traced to a Santa Barbara residence about two hours from the scene. The agency was closed Friday, but investigators were at Mother's Beach where the dog was found.

A California prosecutor who learned of the animal cruelty case speculated that the dog may have been killed in retaliation against its owner, since the tag was present and the dog was left in the open.

Hundreds of people have since shared and commented on the post, in hopes of finding the dog killer.