Dateline returned to some of the most terrifying recent cold cases, and one of the most frightening is the case of Jonelle Matthews, who was 12 years old. She had been missing since December of 1984.

Dateline re-examined one of Colorado's most chilling cold cases—the vanishing of 12-year-old Jonelle Matthews from her Greeley residence on Dec. 20, 1984.

Though suspicions had long surrounded Steven Pankey — a local man with ties to her church who later ran twice for the ...