 She testified that blood found on a sock in Simpsons bedroom was Nicole Brown's with a 1-in-170 million chance of error and that the blood drops next to bloody foot prints near Nicole's body was Simpsons 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.