Byron Case's then-girlfriend Kelly Moffett was interviewed on August 22, 1998 by Jackson County Sheriff's Deputy Gary Kilgore in relation to Anastasia' murder. During the course of that interview, Kilgore administered a Voice Stress Analysis (VSA) test on her. The test itself was found to be defective, and whether she passed or failed is unknown.

Standard polygraph tests (colloquially called "lie-detector" tests) have long been considered notoriously unreliable, and their results are not admissible in court. VSA tests are even more unreliable than polygraph tests,¹ and are generally employed by police only for an attempted psychological advantage against unsophisticated or easily intimidated witnesses. There are many effective methods to beat a voice stress test, methods readily available on the internet and local library, all available to both the killer and his girlfriend at the time.

While Moffett was submitting to this and other interviews, Case himself was categorically refusing to even speak with police, much less submit to any tests. His stated reason for his nearly complete lack of cooperation with investigators has been the standard "advice from his lawyer", though attorneys usually have reasons to give such advice, and Case has never divulged any such attorney's alleged grounds for such reservations.

During pre-trial motions, it was agreed by both sides that no mention of the VSA would be made during trial.² However, Moffett, by that time the state's eyewitness, inadvertently mentioned the VSA she was given during her direct testimony.³ Case and his attorney were offered the option of requesting a mistrial, and they declined the offer.⁴

Jurors were instructed to disregard the mention of the test, and were clearly informed that the test was wholly unreliable.⁵ Since that time, Case and his supporters have focused on two contradictary assertions. First, they have argued that the fact that the witness had even submitted to a VSA test proved that she must have believed in what she said, no matter how the test came out. Second, they have argued that her having inadvertently mentioned the VSA in her trial testimony prejudiced the jury into believing that she passed the test when accusing the defendant of murder. No matter what they believe, the truth is that the VSA was of little to no value legally and was not taken into consideration by jurors during deliberation.

First, as we stated before, the VSA test is an unsophisticated and unreliable test, more unreliable than the standard polygraph; it is primarily used by police for psychological advantage, and methods for beating it are easy to find. Second, the VSA is absolutely inadmissible in court. Both Case and Moffett had nothing to lose by her having taken it; had she passed, they could have used it to get police off their backs; had she failed, she could have fallen back on the test's unreliability. This was a win-win situation for Case; the only surprise is that he didn't take it himself, especially when he was interviewed under limited immunity.⁶