Call Northside 777

The name of this movie is Call Northside 777 released in 1948-02-13 and it's main theme is In 1932, a cop is killed and Frank Wiecek sentenced to life. Eleven years later, a newspaper ad by Frank's mother leads Chicago reporter P.J. O'Neal to look into the case. For some time, O'Neal continues to believe Frank guilty. But when he starts to change his mind, he meets increased resistance from authorities unwilling to be proved wrong..