Updated

The disappearances of nearly 40 dogs from southern Idaho is baffling authorities and raising concerns among animal control officials after dogs were found dead under mysterious circumstances, with one found with its head crushed in a suspected ritual killing.

KPVI reports nearly 40 dogs have been reported missing since November in Twin Falls and nearby communities in an agricultural region in south-central Idaho known as the Magic Valley, with the dogs varying in size, breed and age.

"The dogs seem to vanish into thin air,'' Debbie Blackwood, the director of the animal shelter in Twin Falls, Idaho tells Reuters.

Reuters reports authorities grew even more concerned after a German shepherd was found apparently stoned to death earlier this month.

Blackwood says the dog appeared to have suffered a "ritualistic execution,'' in which its head was crushed with rock and its carcass covered with a purple cloth.

That case prompted the Humane Society to offer a $5,000 reward for information in the killing, but Blackwood tells KPVI the German shepherd was not the only dog found dead under mysterious circumstances in recent months.

“There have been some found with mouth duct-taped shut and then their teeth had been filed off before that so they couldn’t fight back and were used to train dogs as bait dogs,” Blackwood said.

It was unclear if that case was linked to the rash of dog disappearances, authorities said. Dogs have been removed or released from private yards, unleashed from chains or failed to return home after roaming.

"Animals go missing every day. What's disturbing about this trend is that there is absolutely no trace of them," Lisa Kauffman, Idaho director of the Humane Society tells Reuters.

Blackwood tells KPVI they have received multiple reports of dogs being lured into vehicles by an apparent stranger.

John Goodwin, head of animal cruelty policy for the Humane Society, said it was unlikely dogs were stolen by people engaged in dog fighting, which is illegal in Idaho, because it was rare for those involved in the activity to use just any dog.

Twin Falls spokesman Josh Palmer said city officials on Wednesday consulted with the Humane Society and other animal rescue officials about the missing dogs.

Meanwhile, authorities were asking residents to report "any unusual activity, like the stalking or taking of pets,'' he told Reuters.

Click for more from KPVI.

Reuters contributed to this report.