The coldest case ever solved in American history is back in the Cold Case File.

In 1957 Maria Ridolph disappeared from a street corner in Sycamore, Illinois. Her friend Kathy said she and Maria were playing in the street when a young man, calling himself "Johnny", approached and asked if they liked piggyback rides. Kathy went into her house to get her mittens, when she came back Johnny and Maria were gone.

An extensive search turned up neither Johnny or Maria and the disappearance made national headlines at the time. Five months later her remains were found in a wooded area 100 miles from her home. She was 7-years-old.

For years there were no clues or leads to go on, but the department never lost interest in the case. It wasn't until 50 years after the murder that authorities even had a cause of death. Maria died from multiple stab wounds to the throat.

In 2012 police arrested 73-year-old ex-cop Jack McCullough for the murder of Maria Ridolph. McCullough, who went by the name John Tessier at the time, was a neighbor of the Ridolph's and matched the description given by Kathy.

With his conviction the case became the oldest cold case ever solved - until now.

In 2016 the court granted McCullough's request for a review of available evidence. They discovered proof that he couldn't have murdered Ridolph because he made a phone call to his mother 40-miles away from Sycamore.

McCullough's conviction was overturned and a new trial ordered, before that could come to pass a judge dismissed the charges entirely. McCullough filed for, and was granted, a declaration of innocence in 2017.

Now the Ridolph family, after tasting justice so long after losing Maria, is back to grieving.