A Missouri judge has overturned the conviction of Christopher Dunn, who has spent more than 30 years in prison for a killing he has long contended he didn’t commit. Monday’s ruling is likely to free Dunn, but it isn’t immediately clear when. Dunn was convicted of killing a 15-year-old boy in 1990. St. Louis Circuit Attorney Gabe Gore filed a motion in February to vacate the verdict, citing evidence of “actual innocence.” The Missouri Attorney General’s Office opposed the motion. It argued that testimony from two boys at the scene who identified Dunn as the shooter was correct, even though they later recanted.