BVR Speaker Series: Special Agent De LaPeña talks about polygraph tests and the FBI

Posted on January 1, 1970

Special Agent De LaPeña talked to Beaver’s Forensics class about his time as an FBI agent, how a polygraph works, and what it can provide to a criminal case.

As he set up the polygraph machine for the students, he described each part of the machine and talked about how a polygraph machine measures sweat, blood pressure, breathing suppression, heart rate, and movement. He then showed on two students what it looked like on his computer software when their pulse raised or their hands became sweaty. Special Agent De LaPeña then spoke about the countermeasures he does to stop a subject from doing something to control their reactions and influence the polygraph exam physically and mentally like making sure the subjects eyes are open and having nothing on walls in the room to distract them.

“A big part of the polygraph is the interrogation”

Special Agent De LaPeña then talked all about the process he goes through before and during a polygraph exam. Most of the people he gives a polygraph to are either applicants for a job or people who potentially committed a crime. First he background checks the subject by interviewing that person’s professors, neighbors, and former employers.  Then once he knows all about the person, he meets with them to talk and convince them to take polygraph exam by saying, “if you don’t take the test then you must be guilty.”

He then fills out information about the person and performs a practice test. In this test the subject will write a number and then Agent De LaPena will ask questions about which number they wrote and make the subject lie for one of the answers and not lie on the others to create a baseline so he can know when they are lying.

“9 times out of 10 when we test someone, we know or think they did it.”

Most of the time the polygraph results never come in to play in a trial. Instead, they can be used as a tactic to get a subject to confess. When Special Agent De LaPeña has finished a polygraph exam, he then transitions to give the subject an opportunity to talk about the results of the exam and often times they will confess to the crime after seeing proof in the polygraph that they are lying.

Special Agent De LaPeña then taught the class three techniques he uses when interrogating (RPM):

  1. Rationalization: the act of attempting to explain or justify a behavior or an attitude with logical reasons. To do this he would say to the subjects something like, “anyone in your shoes would have done the same thing.” 

2. Projection: the act of putting blame on someone else. To do this he would say things like, “they didn’t train you properly. It’s their fault.”

3. Miniaturization: the act of making an event seem smaller. To do this he would say things like, “it’s not that bad, no one got hurt.”

Special Agent De LaPeña works on the real side of the FBI and criminal justice world as well as on the fictional side. He’s the author of three fictional suspense books about the FBI; The Coyote Wars, The Last Coyote, and Coyote Rising. After the class he raffled off one of his books to students and posed for a group photo.