PALM BEACH COUNTY, Fla. -- The preliminary results of a necropsy on a dog whose owner says it was killed by an exorcism show that the dog was asphyxiated.

The Palm Beach County Sheriff's Office is investigating the death of the German shepherd puppy.

Lisa Berstien said that she took her dog, Ringo, to trainer Jill Deringer after Petco referred her to the trainer. Deringer is employed by Petco.

Berstien said that Deringer came to her home Sunday to perform a procedure on Ringo. Berstien said the dog need to be "exorcised" to "get bad endorphins that made him hyper out of his system."

Berstien said that Deringer muzzled the dog and sat on him. She said that Deringer had her hold her dog's paws still while the trainer barked in the dog's ears and poked the dog in the head and stomach for about an hour.

Berstien said the dog began foaming at the mouth and lapsed into unconsciousness. She rushed the dog to an animal hospital, where it later died.

The necropsy indicated that the dog had become dehydrated and lapsed into unconsciousness before he died.

The state attorney's office is also investigating the incident. Deringer could face criminal charges in the dog's death.