Civil rights activists and legal experts are challenging Sen. Amy Klobuchar’s claims that she was unaware of questionable evidence and police tactics used to send a young black teen to prison for life when she was a top Minneapolis prosecutor. In an interview with “Fox News Sunday,” Klobuchar denied that she had knowledge of any evidence that would call the conviction into question. But much of what The Associated Press found while investigating the case would have been available to her office at the time. The president of the national NAACP says the conviction points to the eagerness of America’s criminal justice system to put young black men behind bars.