This four-part series exposed, for the first time, Minnesota's heavy use of solitary confinement. By building a database and through prisoner interviews, we found more than 1,600 examples of inmates spending six months or longer in isolation over the past 10 years, and 437 instances of prisoners serving one year or longer. We documented more than 24,000 cases of inmates spending longer than 15 days in solitary—the time frame the United Nations defines as human torture. The series also showed how inmates come to prison with pre-existing mental illnesses and end up in isolation only to deteriorate mentally. The final installment told of the difficult path for inmates once they leave isolation. In more than 700 cases in the past six years alone, offenders left prison directly from solitary confinement.