North Carolina’s state bureau of investigation (SBI) laboratory has come under fire recently, after an audit and a series of articles from the Raleigh News and observer. There are at least two articles on blood tests alone. I found the following quotes interesting. Jed Taub, a 30-year veteran of the SBI, said, "’We didn't report the negative result of a confirmatory test because, really, it's misleading,’ said Taub, who now works as a forensic investigator for the Pitt County Sheriff's Office. ‘We couldn't be sure it wasn't blood, so those tests really didn't matter.’"
Mandy Locke and Joseph Neff continued, “Taub said that the only times he reported the absence of blood was when he got a negative result on that first, presumptive test. Any negative results after that were irrelevant, he said.”
Another article in the series noted, “A new audit says more than 200 criminal cases will require official reviews because of questionable blood analysis work by the SBI. Seven involve death penalty cases, three of which have resulted in executions. In at least some of the cases the presumptive test used phenolphthalein (Kastle-Meyer test), but the parallels to the use of luminol in the present case are remarkable.