On Oct. 29, Precinct One Constable Mark Brewer and a sheriff's deputy reported to an animal complaint call.
The deputy's report states Brewer believed the dog was sick or injured and that the dog had a collar, but no tags.
And according to the report, the deputy tried to contact animal control and the humane society but no one answered.
Sheriff David Duke says Brewer offered to take the dog, so the deputy and brewer put the dog in the back of Brewer's truck on a piece of plywood and Brewer drove off.
Duke says minutes later, the deputy got a message from dispatch about someone looking for their dog.
The sheriff says Brewer had taken the dog to the Wichita River, shot it, and disposed of the body in the river.
Constable Brewer faces a felony cruelty to an animal charge.
If he is charged and then found guilty, he could be removed from his elected position.
The Texas Rangers investigated this case, and have now turned it over to the Wichita County District Attorney's Office.