The State Bureau of Investigation has been under scrutiny since February, when Greg Taylor, a Wake County man who had been in prison for 17 years, was exonerated by a panel of judges. At the center of the mistakes that sent him to prison in 1993: a lab report from agent Duane Deaver, a blood expert at the bureau's crime lab, that withheld crucial evidence.

This series, the product of months of reporting, reveals problems far beyond blood analysis. It shows an agency that teaches its agents and laboratory analysts to line up with prosecutors' case theories. In some cases, they ignore or twist key pieces of evidence. In others, rogue agents range far beyond the rules, sometimes with devastating results.

Reporters reviewed more than 15,000 pages of documents detailing crime lab protocol and practices. Many investigative files are not public, but we analyzed dozens of cases through court files and lawsuits, studying the testimony of agents and analysts. We interviewed dozens of lawyers, ballistics experts, lab experts, state officials and those wronged by the SBI's mistakes.