NEWPORT BEACH (CBSLA.com) — An investigation is underway after authorities say the body of a dog with a cinder block tied to its leg was found floating west of the Newport Beach Pier.

The witness who reported it to Sheriff’s Harbor Patrol on Saturday afternoon described the dog as a pregnant pit bull.

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On Wednesday night, as police investigate whether the dog was alive or dead when it was dumped, animal rescue groups and dog owners are demanding action.

“The most devastating part for me is this was something, you don’t walk around with a cinder block in your pocket,” Tracy Hughes of SoCal Animal Rescue (SCAR) said.

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“Someone had a plan and they went and got the cinder block and tied it to this poor animal’s leg and threw it to the bottom of the ocean,” she added. “It wasn’t an accident. Someone did this on purpose.”

If someone couldn’t afford a proper burial or could no longer take care of the dog, many rescues would have stepped in to help, said Hughes, who runs SCAR.

Deputies suspect that the dog had been underwater for about one week.

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Animal control officers say they don’t believe they’ll be able to perform a necropsy to find out the cause of death because the dog was so badly decomposed.