CHICKAMAUGA, Ga. — Authorities in northwest Georgia say a man shot and killed a 72-year-old who he thought might be an intruder but turned out to be a wandering Alzheimer’s patient.

Walker County police told the Chattanooga Times Free Press that Ronald Westbrook had walked about 3 miles in the sub-freezing temperatures before knocking on Joe Hendrix’s door just before 4 a.m. Wednesday.

Hendrix’s fiancee didn’t answer, instead calling police. Sheriff Steve Wilson said before deputies arrived, Hendrix went into the backyard with his handgun, and gave Westbrook several verbal commands, but the Alzheimer’s patient didn’t respond. Hendrix then fired four shots.