On this day, Dec. 28, in 1956, sisters Barbara and Patricia Grimes disappeared from a Chicago movie theater.

The girls, ages 15 and 13, respectively, went to see the Elvis Presley movie "Love Me Tender" but never made it home.

The investigation began as a missing-persons case. Police questioned 43,740 people and interviewed 3,270 suspects. Even Elvis urged the girls to return home.

On Jan. 22, 1957, the girls' naked, frozen bodies were discovered along a rural road.

The unsolved crime shattered the innocence of the '50s and has been called by some historians Chicago's greatest unsolved mystery.

- Scott McCabe