Polygraph examinations aren’t just used for catching the bad guy; Michigan State University Police Detective Anne Stahl knows that first-hand.
Stahl, the only polygraph examiner in the department, also has used polygraph examinations to prove someone's innocence.
“The polygraph is an investigative tool,” Stahl said. “It is great for identifying suspects and eliminating suspects. Ultimately it’s about helping out the department in their investigation.”
No matter the purpose, Stahl always follows the same routine:
- Give the examinee a brief overview of the polygraph test and explain the process.
- Get the examinee’s consent.
- Complete the medical background form and learn more about the examinee’s background and lifestyle.
- Describe the components of the polygraph instrument and explain to the examinee how polygraph works with the human body and mind.
- Go over the incident and allow the examinee to explain the situation in their own words.
- Formulate the questions that will be asked during the exam and go over them with the examinee.
- Administer a practice test so the examinee can get acquainted with the machine.
- Begin the polygraph testing phase.
- Evaluate the charts or results and formulate an opinion to discuss with the examinee.
One polygraph examination can last up to three hours, but Stahl says she doesn’t mind the time investment because she truly enjoys what she does.
“I have always loved the study of physiology and psychology, so when you put those things together, polygraph is just a great fit for me,” she said.