The article says Father was in the rectory with his dog, apparently making coffee, when he was attacked. Then no further mention of the dog. A dog will fight, bark, attack, run for help, etc, if possible to defend its master. Or maybe the dog was hurt or killed, I wish they specified.
If the dog is alive, and they have suspects (such as vagrants that have been hanging around the church, or anyone who was heard to threaten the priest, mentally ill parishioner, whatever the case may be), the dog could help identify the killer. Dogs are incredible. Put that killer in front of the dog and believe me you are going to get a strong reaction. That’s not enough for proof beyond a reasonable doubt, but certainly it could help narrow down possibilities if there are several suspects.