A polygraph machine does not actually detect if a person is telling the truth. The machine measures a person’s physiological reactions while hearing questions and answering those questions. The machine measures things like a person’s pulse, breathing, and blood pressure. The polygraph examiner asks control questions to get a base level of these physical reactions. Then, the examiner compares the person’s reactions during the answering of the control questions to the person’s reactions when answering the questions about the criminal investigation. Based on changes in the person’s physical reactions, the polygraph examiner can detect if the person is telling the truth.
The results of a polygraph exam are generally not admissible in criminal trials in Missouri. See State v. Biddle, 599 S.W.2d 182, 185 (Mo. banc 1980). However, the results may affect whether a police officer or prosecutor will believe you are innocent or guilty. If you are innocent but fail a polygraph exam, it is likely that the prosecutor will think you are guilty and will then view all other evidence with a mindset that it supports your guilt.
In the past, our firm has hired well-respected polygraph examiners to “test” our clients privately to see the results before allowing our clients to take a test with the police. Also, because we use well-respected polygraph examiners, the police on occasion have accepted the results from the examiners we hired. So call Cantin Mynarich LLC to speak with one of our attorneys before taking a polygraph exam.