Maria was the pretty one, slight and graceful at 7 with big brown eyes that shined with warmth and intelligence. Everyone said the second-grader was special and Kathy, who was a year older, felt honored to be her friend.

They lived a few doors away from each other on a side street called Archie Place. It was their whole world in 1957, a time when children played hide-and-seek outside instead of watching television. People didn’t lock their doors in this Midwestern farm town because everyone knew everybody else.

Sycamore and its 7,000 souls felt safe on the morning of December 3, 1957, but the feeling wouldn’t last.

That first Tuesday in December started like any other for Maria Ridulph and Kathy Sigman, with a short walk across the street to West Elementary School. It was cold, with a promise of snow in the air. After school, they went to Maria’s house to cut out paper snowflakes.

A few blocks away, a man in an overcoat spotted two other girls walking along State Street by the public library and tried to strike up a conversation. It was 4:15 p.m. The girls felt uneasy, so they ducked into a restaurant. When they emerged, the man was gone — but he’d left something disturbing behind. Scattered on the sidewalk were half a dozen photographs of nude women.

That wasn’t Sycamore’s only peculiar hint of the dirty and forbidden. Since Halloween, someone had been scrawling obscenities in chalk on a tree and stop sign at the intersection of Center Cross Street and Archie Place. Maria and Kathy made plans to play there after dinner. It was a favorite spot they hadn’t been to since summer.

At 5 p.m. sharp, Kathy went home. Maria’s family gathered around the table for her favorite supper: rabbit, carrots, potatoes and milk. She finished off two rabbit legs, but barely touched her vegetables. She pleaded to go back outside as the first flurries of the season started to swirl in the night sky.