PHOENIX (AP) -- The Arizona Department of Corrections says one of its dogs has died under circumstances that warranted a criminal investigation. The dog died April 9 at the Lewis prison complex in Buckeye and the case was referred Thursday to the Maricopa County Attorney's Office. County Attorney officials say they're reviewing the matter and no charging decision has been made yet. DOC spokesman Bill Lamoreaux says little information can be released on the dog's death, including the cause and exactly where in the prison complex the animal was when it died. Lamoreaux says the death wasn't related to an inmate. An administrative investigation will be conducted once a DOC employee connected with the matter returns from leave. The DOC uses dogs for various purposes, including tracking escapees, extracting people and sniffing contraband.