How do people reason about complex bodies of legal evidence? The story model of juror decision-making posits that people construct stories to determine guilt. But the story model does not model how evidence items relate to elements within the story, how the credibility and reliability of the evidence (e.g., witness testimony) is assessed, or how this affects story evaluation. Recent empirical work suggests that people reason using qualitative causal networks. In two studies mock jurors read a real legal case and judged the probability of the defendant’s guilt, the credibility of the victim and of key witnesses. Study 1 showed that an inconsistent testimony decreased the victim’s credibility and defendant’s guilt, also increasing the defendant’s credibility. Study 2 replicated this finding with a different population. These findings suggest that people draw inferences about credibility and reliability of evidence that filter into their network of beliefs about the crime.