Belfast-born Mr McCullogh was indicted in 2011 on charges of the kidnap, rape and murder of seven-year-old Maria Ridulph in 1957, and was convicted in the subsequent trial. He was given a life sentence with the possibility of parole after 20 years.

However, Mr McCullogh’s conviction was overturned after a successful appeal in 2015. On Wednesday, a US court went further and formally granted him a certificate of innocence after new evidence emerged.

In the Circuit Court for the 23rd Judicial Circuit of the State of Illinois, Judge William Brady ruled: “The ultimate question that must be answered herein is: Is it more likely that the defendant would be found guilty beyond a reasonable doubt or is it more likely that he would be found not guilty and not responsible for Maria Ridulph’s disappearance and murder.

“Based on the changes in the law and the consideration of the additional evidence now available to this Court that may not have been available to the trier of fact, the latter of these questions is true and, thus, Mr. McCullough’s petition is granted and counsel for Mr. McCullough shall prepare the appropriate orders requested.”