Your theory would explain the calls to the other owner of the dog AND possibly the police saying they found a door open...
Here's the Q & A from the Moscow, Idaho website:
- What happened to the dog?
On the night of the incident, officers located a dog at the residence. The dog was unharmed and turned over to Animal Services and later released to a responsible party.
Note: "On the night of the incident...."
To me, it's weird that the dog was turned over to Animal Services if it was any other time except the night of the incident when none of the occupants of the home had discovered he was missing.