Perhaps a tragic accident, perhaps a foreseeable problem.
She escaped her yard.
I wish that police departments would require a double containment system for police dogs. A kennel within a fenced yard.
If this dog was left outside in a yard, shame on them. GSDs can easily climb over fences, dig under fences, clear fences, that they should never be trusted alone in a yard, unless there is more than a simple fence.
I would hope that if the officer was out there, he should have been able to control the dog.