A true-crime book titled "Marple's Gretchen Harrington Tragedy" may have helped lead to an arrest in the nearly 50-year-old cold case murder of an 8-year-old girl.
Joanna Sullivan, co-author of "Marple's Gretchen Harrington Tragedy," credit her writings for helping police arrest David Zandstra for the 1975 disappearance and murder of 8-year-old Gretchen Harrington.