 The claim was refuted by the defenses own witness, FBI special agent Roger Martz who showed the level of EDTA in that blood drop is consistent with unpreserved blood and not even close to the levels that would be seen in blood from a purple top tube.The prosecution also countered that no blood was ever claimed to be missing from Nicole Brown's reference vial and that the records show Detective Vannatter booked the reference vials from the victims immediately into evidence right after receiving it from Deputy Medical Examiner Dr. Irwin Golden.Dr.