The death of the dog that was placed in the overhead bin on a United Airlines flight has triggered a criminal investigation.

The Harris County, Texas D.A. has assigned the case to the animal cruelty division.

The D.A. did not disclose the target of the investigation. As we reported, the flight attendant who ordered the dog owner to place her pet carrier in the overhead says she was unaware there was a dog inside. The odd thing is ... the dog was barking loud enough for passengers to hear for a prolonged period of time before it died.

United has apologized, but that clearly is not the end of this story.