Under the microscope: The SBI story so far

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.

Deaver kept a secret that was critical to Taylor's prosecution: A conclusive test showed that material on Taylor's truck wasn't blood, even though Deaver filed a report with prosecutors saying that the truck gave chemical indications for the presence of blood. He later testified that his bosses told him to write his reports in that way.

Attorney General Roy Cooper, who oversees the SBI, launched an external audit of the serology unit.

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.