Suspected criminals will find it a lot tougher to lie to Slidell police now that Sgt. Nicky Mistretta has become the department’s only polygraph operator.

Mistretta, a 12-year veteran with the Slidell Police Department, recently finished an intense 10-week course at the American International Institute of Polygraph in Atlanta. Mistretta is the department’s first polygraph examiner in 20 years, said Chief of Police Freddie Drennan.

The polygraph, commonly known as a lie detector, is a tool used by police to find out if a suspect is telling the truth. Mistretta said the term “lie detector” is a misnomer, and that the machine and the operator use a combination of physiological and psychological components to tell if a person is either lying or telling the truth.

Sgt. Nicky Mistretta busy at work reading the results of a polygraph test at the Slidell Police Department. (Staff Photo by Erik Sanzenbach)

Mistretta said a polygraph test can help police develop further leads in a case or help strengthen a case by helping to reveal information known only by the perpetrator. The sergeant said a polygraph can also help by eliminating suspects who are actually innocent.

“I didn’t know much about it when I started the course, but now I’m convinced it’s a very accurate tool for the police department,” Mistretta said.

Drennan stressed the polygraph is a “tool used in the investigative process” and not the final say on guilt or innocence.

One of the reasons Drennan sent Mistretta to the polygraph school was to save the department money. Even though the course cost the department $25,000, and it cost another $5,500 for the polygraph machine, Drennan said the money saved will be worth the expense.

“It will pay back the department what we spend for outside polygraph contractors,” Drennan said.

The chief said a private polygraph contractor usually charges about $125 an hour. That gets very expensive for the police department, considering it polygraphs many suspects, plus every person who applies for a job with the department must undergo a polygraph exam. Mistretta said it takes about two hours to administer a polygraph exam, which also adds to the cost of a contractor.

Mistretta said it takes so long because there are three phases of the exam. First, Mistretta must interview the subject for an hour before the actual exam. The interview is to tell the subject exactly what the polygraph is and what to expect. While this is going on, Mistretta is developing a psychological profile of the subject so that he can ask the appropriate questions. Mistretta said constructing the questions is a big part of the process.

“The pre-interview makes them understand how the fear of a lie will set off the machine,” Mistretta said.

The second phase is the actual testing, where the subject is hooked up to the machine with sensors that measure breathing, sweat gland activity and blood pressure. Finally, there is the post-test evaluation where the graph is looked at for possible lies.

“The hardest part is reading the chart,” Drennan said.

Mistretta said the 10-week course was very intensive. Classes were eight hours a day, five days a week, with homework. Before he actually learned about the machine, Mistretta had to take courses in physiology and psychology. The course not only taught him how to use the machine, but it helps him in his regular police work. Mistretta has worked with the narcotics squad in the Investigation Division for the past 10 years. The lessons he learned at the polygraph school helped him in normal interrogation of suspects.

“You learn how to read body language and to see how people react to questions,” Mistretta said.

Assistant Chief of Police Jesse Simon added Mistretta’s work will also save the department money in recruiting officers. It costs the department about $20,000 per candidate from the day of hire, to the first day the recruit hits the street.

“If we find something amiss at the beginning, it means we don’t have to spend the money on training that person,” Simon said. “It’s a tremendous asset for pre-employment. We’ve already caught several applicants in a lie.”

Mistretta still has a ways to go before he becomes a licensed polygraph operator in the state of Louisiana. He has to finish a six-month internship in which he has to administer a certain number of exams under the guidance of a sponsor. Mistretta’s sponsor is a Mandeville police officer who is a licensed polygraph operator. So far, Mistretta has administered about 80 tests, and seven of those have been on applicants with the Slidell Police Department.

After the internship, Mistretta will go before the state’s Board of Polygraph Examiners to take a final exam in order to be licensed.