analysed results provided by FBI special agent Roger Martz, testified that the level of EDTA in the evidence samples was higher than that which is normally found in blood: this appeared to support the claim they came from the reference vials. During cross-examination, Clark asked Dr. Rieders to read out loud the portion of the EPA article that stated what the normal levels of EDTA in blood are, which he referenced during his testimony. This demonstrated that he misread it and that the levels found in the evidence samples were consistent with those found in blood that was not preserved in a police reference vial. Dr. Rieders then claimed it was a "typo" but the prosecution produced a direct copy from the EPA confirming the normal amounts of EDTA found in unpreserved blood. The prosecution also had Dr. Rieders admit that EDTA is also found in food and specifically the ingredients used in McDonald's Big Mac and French fries that Simpson had eaten earlier that night with Kato Kaelin. FBI special agent Roger Martz was called by the defense on July 25, 1995, to testify that EDTA was present in the evidence samples, yet instead said he did not identify EDTA in the blood, contradicting the testimony given by Dr. Rieders the day before. Initially, he conceded the blood samples "responded like EDTA responded" and "was consistent with the presence of EDTA" but clarified his response after hearing during the lunch break that "everyone is saying that I found EDTA, but I am not saying that". When the defense accused their own witness of changing his demeanor to favor the prosecution, he replied "I cannot be entirely truthful by only giving 'yes' and 'no' answers". Martz stated that it was impossible to ascertain with certainty the presence of EDTA, as while the presumptive test for EDTA was positive, the identification test for EDTA was inconclusive. Martz also tested his own unpreserved blood and got the same results for EDTA levels as the evidence samples, which he said conclusively disproved the claim the evidence blood came from the reference vials. He contended that the defense had jumped to conclusions from the presumptive test results, while his tests had in fact shown that "those bloodstains did not come from preserved blood". Back gate The defense alleged that Simpson's blood on the back gate at the Bundy crime scene was planted by the