Marc LeBeau

FBI chemist Marc LeBeau testified in Steven Avery's 2007 Wisconsin trial about a laboratory method developed to test dried bloodstains for EDTA, an additive in the stored blood tube at issue. On Day 16, he described the method's validation and reported that three bloodstain swabs from Teresa Halbach's RAV4 showed no detectable EDTA or iron-bound EDTA, while blood from the purple-topped tube tested positive. He concluded that the tested stains did not come from that tube. After testimony and argument about the method, the court admitted his opinion.

On Day 17, LeBeau presented the comparison to the jury. The court sustained a defense objection when the prosecutor sought to turn his result into an unrestricted conclusion that no evidence had been planted. Buting's cross-examination tested the case-specific protocol, its internal review, blind-testing practices, detection limits, and evidence about EDTA stability. LeBeau defended the testing but agreed that nondetection did not establish absolute absence of EDTA; he also clarified that his tube-source opinion did not rule out planting from a source without EDTA.

Buting also questioned LeBeau about a later change in the interpretation of his testing in the Sybers case. On redirect, LeBeau explained the later trace findings and said he had notified prosecutors. On recross, he said he did not know whether Sybers's guilty plea resulted in time served and immediate release.