Police
After they settled everything with Jackson, they didn’t let him go into the backyard anymore, or Noah as a matter of fact. They weren’t taking any more chances, they knew that there was someone out there who had a BB and liked to use it in sadistic and cruel ways.
It was time to call the police, which is exactly what Hayden went out and did. She notified them and let them know about what happened and that she wanted them to come and investigate who had shot her dog. The police arrived and the investigation was formally underway.