 The claim of EDTA on the sock coming from Nicole Brown's reference vial was conclusively disproven by Dr. Cotton who showed the DNA in the reference vial was more degraded than the DNA on the sock, proving it could not have come from that vial.FBI Special Agent Roger Martz testified on July 25 and July 26, 1995.The defense called Agent Martz because Dr. Rieders had used his data during his testimony.