Buried at the edge of a Chicago Catholic cemetery are an elderly person’s remains marked only by a cement cylinder deep in the ground labeled with the numbers 04985. The person died in 2015 at a nursing home not remembering much, including their own name.They went by Seven. Now police specializing in missing people and cold cases have discovered Seven’s identity in one of the most unusual investigations the Cook County sheriff’s office has pursued and one that could change state law. Using post-mortem fingerprints …