 Because EDTA is used as a preservative in purple top tubes for lab draws, he stated the blood could have come from their reference vials.During cross-examination the claim was immediately debunked when the prosecution gave Rieders a fax copy of the EPA article he referenced during his testimony and had him read it out loud to the jury demonstrating he misread it and it does say "parts-per-million" of EDTA is normally found in blood.Rieders then claimed it was a typo but the prosecution produced a certified copy directly from the EPA, confirming the PPM units of measure.