Tyler Muzzi noticed a stranger walking around a neighbor's home in Cleveland, Mississippi, on June 12.
Muzzi called the neighbor, Bryant Steele, who then called the police.
Officers arrested the unidentified man, who reportedly entered Steele's house, without incident.
Moments later, Muzzi heard gunshots outside. A police officer informed Muzzi that his dog, named Miller, had been shot, reported The Clarion-Ledger. The dog later died.
Miller was secured to a leash when the cops arrived, but Muzzi claims a police investigator told him he didn't see that the dog was on a leash, felt threatened and shot Miller.
Nick Barone, who heard about the shooting online, created a Facebook page called Justice 4 Miller Muzzi.
Bethany Harris Muzzi, Tyler’s wife, wrote on the Facebook page on June 13:
"So Tyler goes to our backyard to see everyone standing around miller while he whimpers. Tyler, by himself, ran to get towels and wrap Miller up to get him to the vet. We received a phone call an hour later saying the shots severed his spine and we needed to come say goodbye.
"We thought by having our year and a half old lab puppy in our backyard on a line, he was safe. We are devastated and will find out soon what is going to happen about all of this. Please continue to pray. We just want justice for our baby!"
The police investigator has been placed on administrative leave.