I shot one in the early 70's thats liver had a similar color. It was in California maybe 30 miles North East of Santa Barbara.

A Forestry worker came by as I was gutting it, we decided burying it and piling rocks on top was the best choice at the time. He supplied the shovel and even helped me dig, nice guy.

He suggested it was TB or some other disease. I was thinking maybe it had been drinking at some puddle covered in Blue Algae, which is a similar color (and poison).

They also make a Rat poison, poison Corn, that is that color (old school). Though they have changed the color to red recently (in the last half dozen years).

It really isn't unusual in the dry parts of California for small ranchers to poison Deer. The wildlife brings in disease and competes for food and water with the livestock. One reason they don't want you hunting their property is to avoid witnesses and evidence.