DURHAM, N.C. (AP) — Evidence of prosecutorial misconduct that could exonerate a man who has spent 21 years in prison for a double murder will be at center stage during a hearing in a North Carolina courtroom this week.

A judge two years ago threw out Darryl Howard’s 1995 conviction but an appeals court ruled a new hearing was needed. He remains imprisoned.

The hearing starting Monday could highlight whether evidence that could have proved Howard’s innocence was withheld by prosecutors and police.

Superior Court Judge Orlando Hudson said in 2014 he remembered observing Howard’s murder trial as it was under way. He called it “a horrendous prosecution” that ignored that “there was extremely credible, strong evidence that Mr. Howard did not commit” the crime.