DNA sibling probability ratios of 159,000:1 (Cofiler) and 6,300:1 (Profiler), calculated using a 3% theta value applied to a Western Australian Aboriginal database without a confidence interval for sibling calculations, were held to be reliable and sufficient, in combination with non-DNA circumstantial evidence, to sustain convictions beyond reasonable doubt. There is no obligation on the prosecution to adduce evidence of alternative DNA calculations based on the defence case. The jury's forensic advantage in assessing witness testimony about physical descriptions may resolve residual doubt about the sufficiency of DNA evidence to exclude a sibling as the offender.
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