blood unaccounted for he stated that peratis didn't document how much was taken from simpson so there is no way to prove that blood is actually missing. he noted though that small amounts of blood do stick to pipettes, gloves, and other lab instruments during testing so that could possibly explain some blood being unaccounted for. robin cotton dr. robin cotton, lab director of cellmark diagnostics, testified may 8–15, 1995. she testified to restriction fragment length polymorphism (rflp) testing, the most precise dna-matching at the time. she testified that blood found on a sock in simpson's bedroom was nicole brown's with a 1-in-170 million chance of error, and that the blood drops next to bloody footprints near nicole's body was simpson's with a 1-in-9.7 billion chance of error. during cross examination, she admitted that two cross contamination errors had occurred at cellmark in 1988 and 1989 but the errors were found during quality control tests and had not occurred since. she stated the dna sample sizes needed for rflp testing in this case are too large to be susceptible to the degraded dna cross-contamination the defense alleged. the only possible scenario would be a mixture of two persons dna being typed, simpson's and the "real killer" if cross-contamination occurred, but only simpson's was found. she admitted her tests cannot demonstrate how the blood got on simpson's sock, meaning her tests do not refute the possibility the blood was planted. gary sims criminalist gary sims of the california department of justice crime lab testified may 16–22, and again from may 31 to june 1, 1995. he testified to the results from dq alpha dna matching. his results also showed nicole brown's blood on the sock found at rockingham with a 1-in-7.7-billion chance of error, the blood on the back gate at brown's home matched simpson and the blood found inside the bronco belonged to the two victims with a 1-in-21 billion chance of error for both. during cross-examination the defense insinuated the matches were from the results from cross-contamination. sims denied this stating that none of the 108 exhibits tested showed evidence of contamination and also mentioned the defense was offered the chance to test the evidence samples for contamination themselves but they declined. gary sims testified again on may 31 and had the jurors look at the socks from simpson's bedroom with their naked eye and then through a microscope. the purpose of this demonstration was to show the blood stains were only visible under a microscope. during recross-examination sims acknowledged that foliage can contaminate blood samples but denied that occurred on the drop of blood on the back gate at brown's home. the defense then asked if that blood could have been planted by the police since it was collected on july 3 and fung said he didn't see it in the photo the defense showed him from june 13. sims denied the claim and said a different photo of the same gate taken on june 13 shows the blood was already there. renee montgomery criminalist renee montgomery of the california department of justice crime lab testified from may 23–24, 1995. she reported the results from d1s80 dna matching, narrating her results using a poster board to reconstruct the prosecution's theory of how the crimes were committed. her results showed that simpson was present during the murders as evidenced by his blood being found next to the bloody footprints next to the bodies. her results show that he fled the scene through the back gate as evidence by his blood found on a trail of blood drops leading away from the victims towards and on the back gate. her results then show he got in his bronco and drove home as evidenced by the victim's blood found on the door outside and inside on the console of the bronco. her results then show he entered his home through the backyard as evidence by a trail of blood stains with his and the two victims found leading behind his home and the bloody glove found behind his home that had blood from all three. her results suggest he changed his clothes prior to meeting the limousine driver as evidence by his sock he left in his bedroom having nicole brown simpson's blood on it. during cross examination, when asked about mishandling of evidence at the crime scene, she stated none of the mistakes they made would add simpson's blood to the evidence unless it was already there. when asked about cross-contamination with simpson's preserved blood at the lapd crime lab, she stated that all of the evidence she testified to, except the glove and sock, were shipped directly to her and not handled by anyone in that lab. when asked about the dna on the glove being degraded after being kept unrefrigerated and then contaminated by simpson's preserved dna, she denied that happened at the lapd lab. if all the dna was degraded and then contaminated with simpson's blood, only simpson's dna should be on the glove. the fact that the victims' blood was found as well is proof that that did not happen. when asked about the reliability of her relatively new test, she stated that it was the same test the fbi was currently using and was accepted in every courtroom in the country, as reliable science. defense case and witnesses "compromised, contaminated, corrupted" the defense stated the dna evidence against simpson was not reliable. they said the police compromised the evidence by committing several mistakes when collecting it including occasionally not changing gloves between evidence items, using one swatch to collect blood from three drops of blood on the bronco dashboard, packaging the swatches of blood evidence using plastic bags, not paper bags as recommended, and storing them in a police van for up to seven hours unrefrigerated. this resulted in 100% of the "real killers" dna being lost. they argued that simpson's blood found on the evidence samples resulted from contamination in the lapd crime lab with the reference blood in all but three exhibits. the remaining three exhibits that could not be explained by contamination were planted by the police. although evidence of mistakes made during collection were shown at trial, no evidence of their contamination or corruption claim was presented. the contamination claim was dependent on all the blood in the case being 100% degraded and the real killer's dna lost. if that did not happen, contamination would only produce a mixture of simpson's dna and the killers. the contamination claim likewise would spread edta to the evidence samples which could be tested for as it was a preservative found in the reference vials of simpson and the two victims. the contamination claim was also limited to just the lapd crime lab as it was not alleged at the two consulting labs, the state department and cellmarks diagnostics, were most of the dna testing was done. the defense also declined to test the samples themselves for the “real killers” dna or for edta. once the prosecution began showing evidence the samples were not completely degraded and no edta was found in levels seen from the reference vials, the defenses reasonable doubt theory became increasingly more dependent on the claim the evidence was corrupted by a police conspiracy to frame simpson. the predominantly african american jury was receptive to it.: 11 edward t. blake dr. edward blake was retained by simpson's defense team to discredit the dna evidence. blake is a world-renowned forensic scientist who pioneered the establishment pcr testing as a reliable forensic science. the prosecution had tried to retain blake before learning the defense had already done so. all of the dna experts were familiar with blake and gary sims, who ran the state department lab, was one of his students. he was slated to testify but was dropped from the witness list on march 30, 1995. after concluding his review of the case, he informed the defense that his testimony is not likely to be helpful. his review found nothing negative to say about the tests from the state department and cellmark diagnostics, concluding those results are likely valid and if he testified he would have to turnover his reports stating the reasons why he reached that conclusion. he was subsequently replaced by microbiologist, dr. john gerdes. john gerdes dr. john gerdes testified from august 2–4 and august 7, 1995. prior to his testimony, the prosecution asked to limit his testimony to just evidence of contamination in this case only but judge ito allowed him to testify about other cases of contamination as well, which they said would be misleading to the jury. during direct examination he testified "the lapd crime lab has a substantial contamination problem. it is chronic in the sense that it doesn't go away." gerdes testified that because of the lapd's history of contamination, he would not consider any of the pcr results, in this case, valid because they were done by the lapd. he testified that both the state department and cellmark diagnostics had made cross-contamination errors in the past too. he testified their pcr results are not valid either because the evidence they tested went "through the lapd" for packaging and shipping. the three rflp matches he admitted were valid. prior to his cross-examination, journalists had already observed his testimony was unreliable as he was clearly pandering to defense, noting the only three dna tests he said were valid were the same three the defense claimed were planted. if he had said those were the result of contamination, he would have contradicted the defenses corruption claim. his claim that “you can no longer have any scientific confidence in” a newly available rflp match linking ron goldman to simpson's bronco because the tow-truck driver had stolen items from it was also mentioned as proof he was pandering. they claim the reason gerdes said that is because earlier he said rflp results are not susceptible to contamination because the amount of dna needed for that test is too large but the defense claimed those three exhibits were planted. now the prosecution had a new rflp match to goldman's blood in the bronco that couldn't be explained by contamination or fraud, so gerdes made that claim instead. during cross-examination gerdes admitted having no experience or training in forensic evidence gathering or forensic dna testing and had never done any of the tests whose results he was criticizing at trial himself or at his lab. he has testified in 23 trials; consistently for criminal defendants charged with rape, murder or both, claiming the dna evidence against them was unreliable because of contamination. he also admitted making the same cross-contamination error he criticized the lapd, state department and cellmark's lab had made in prior years, at his own lab as well. he also admitted the lapd's crime lab has more safeguards in place against contamination than his own lab. when judge ito instructed gerdes to narrow his testimony to facts about this case during cross, journalist noted his demeanor changed as his contamination claim became more dubious. he claimed it was possible for 100% of the "real killers" dna to degrade so every molecule was gone in the seven hours they had spent unrefrigerated in the police van but then admitted that scientists had gotten analyzable dna for pcr tests from mummies and even fossils. he also admitted that contamination for the results at cellmark's and the state department could only have occurred at the crime scene since lapd packaged and ship most of the evidence they tested directly there. if that is where contamination occurred, that means simpson's blood was at the crime scene. he later admitted that in the civil trial. he finally admitted there was no evidence cross-contamination occurred in this case and he was only testifying to "what might have occurred and not what actually did occur". during the civil trial, gerdes testified again. this time he was only allowed to testify about confirmed contamination in this case and admitted "there's no direct evidence of contamination in any of the test results that i looked at in this case." henry lee dr. henry lee, director of the connecticut state forensics science laboratory, testified on august 23–25 and august 28. during cross-examination lee stated dr. gerdes