Even though polygraph test results usually are inadmissible in trials, the Missouri Supreme Court is setting an accused murderer free because a judge excluded them, reports the St. Louis Post-Dispatch. The ruling will result in the release of Sandra Kemper, who was accused in the fire death of her son, 15. A judge declared a mistrial because the jury heard evidence about a polygraph test; a retrial would amount to double jeopardy, the Missouri Supreme Court ruled.
Four months after the fire, Kemper was given a polygraph exam by a police detective. She denied setting the fire, but the examiner told her she had failed the test, and she later made two confessions. The defense said Kemper actually had passed, and argued that the jury needed to know about the polygraph to see that her confessions were coerced with a lie. Said Chief Justice Michael Wolff, concluding that a mistrial should not have been declared: “The results of a polygraph examination generally are inadmissible in Missouri criminal trials. In this case, however, it would have been unfair to Kemper to keep from the jury the results that indicated she had actually passed the test, not flunked it as she had been told. The polygraph test and results are admissible because they formed the circumstances surrounding the confessions that are the basis of the state’s case.”