An Illinois prosecutor says he's convinced that a man convicted in the 1957 killing of a 7-year-old girl couldn't have committed the crime.

DeKalb County State's Attorney Richard Schmack announced the findings Friday after reviewing evidence in the case of Jack McCullough. The court-ordered, six-month review was prompted by McCullough's push for a new trial.

The girl, Maria Ridulph, vanished from the small community of Sycamore on Dec. 3, 1957, and her body was found several months later. The slaying remained a mystery for decades.

McCullough, a neighbor at the time of the slaying, had long ago been cleared by authorities. But he was charged in 2011 during a renewed effort to solve the case. He was found guilty in 2012.

But Schmack says new evidence firms up an alibi.