Did you bother to read the article? They were on their own farm! The father would have no reason to believe that someone on his own property would do something so horrific to his child.
"the father and daughter were at their barn with several other people to groom and care for horses there."Not to pick nits but this left me with the impression that horses might have been boarded at this barn that were not owned by the father. My experience with such (having boarded horses at farms owner by others) is that while the barn may have been owned by the father, it was also something of a public place.
BTW, I didn't convey any blame to the father, I simply asked an honest question.