The Australian Kelpie mix, who was discovered dead in a closed crate near Arakawa's body at the couple's home, likely died from severe dehydration or starvation, according to a report from New Mexico Department of Agriculture obtained by NBC News.

"The stomach was mostly empty except for very small amounts of hair and bile," a veterinary pathologist stated in the document. "The large intestine was mostly empty except for very small amounts of green, thick and pasty feces that was mostly hair."

Though Zinna -- one of Hackman and Arakawa's three dogs -- displayed "severe postmortem decomposition with partial mummification," investigators found "no evidence of an infectious disease" or trauma that could have led to her death, per the report.

According to the pathologist, "If the dog was in a confined space without access to food or water, the dog most likely died of dehydration/starvation."