FOIA on Martin Luther King

Read from the scan by GLM-OCR; expect the odd misread word.

polygraph. Standard polygraphs are four variables: pulse, blood prespiration and perspiration. Some measure additional physiological vari-

The more variables measured, the reliable the polygraph.

1 and McQuiston discovered that the encies composing the human voice ot fixed: they shift very slightly from to fourteen times every second. But the speaker is under stress, this norrequency modulation disappears. remains are the pure component freies of the voice. And a strong indicat the speaker is lying.

e two men developed a device to test this phenomenon and planned to use an additional "channel" on the poly- Then they discovered that the new ole was so reliable and accurate aure of psychological stress there was no need to measure the other polyvariables.

ed from the necessity of strapping the ct into a chair, stretching a pneumoic tube across his chest, gluing elec to his palms. and clamping his arm blood-pressure cuff, the PSE proved much more versatile than the poly. Because it can work from a tele- or tape recorder, the PSE can be without the knowledge or even the cal presence of the subject.

ked Colonel Bell to tell me about some things the PSE was being used for, usually cases in which a conventional graph couldn't be used. He mentioned the police in Howard County, Maryland, been using the PSE for two years; they had great success in establishing theence of suspects who were afraid to it to a polygraph examination because machine's forbidding aspect.

I went on to describe some of his ion's other uses, actual or potential. and the Federal government are exg its use as a defense against skyjackd telephoned bomb threats, and as ns of speeding up customs inspecSome doctors and psychiatrists are PSEs to study patients' physical and stress. The National Committee to igate Aerial Phenomena, a private that investigates UFO reports, is using the PSE to interview witnesses sightings.

ked Bell if he would lend me a PSE eriment with, in order to write a piece the device. He agreed, with two concourse was held in the meeting room holiday Inn in Falls Church, Virginia. eight other students were employees tomers who had purchased the These included a private detective in Pennsylvania, a New York chain

First, I must take Dektor's three-day in operating the instrument; second, using the PSE, I must review my metation of its output with his staff, interest of accuracy. This seemed rea- ce, so I agreed.

African country. The instructor was Mike Kradz, a criminologist and retired police officer. Kradz projects the tough-cop image, but he is a living rebuttal to the Polish joke. There is nothing about forensic science, from fingerprints to polygraphy, on which the man is not an expert.

The first morning of the course was devoted to the physical operation of the PSE. The device is used in conjunction with a Uher tape recorder, which has four speeds and can be manually wound back to locate a particular point on the tape. The testimony to be evaluated is recorded at a tape speed of 71/2 inches per second, then played back and stopped at the beginning of the utterance in question. The recorder is slowed to 15:16 inches per second and played. The sound, no longer recognizable as a human voice, is a long, low rumble.

The PSE itself is built into an attach case. The case opens to reveal a chart drive, similar to an electrocardiograph, and a number of buttons and knobs. A single cable connects the PSE to the tape recorder.

As the tape recorder reels slowly turn, and a rumble issues from its speaker, the PSE stylus dances back and forth across the moving chart paper, leaving behind a ragged trail. Then the recorder is stopped, the chart paper is stopped, and that's all there is to it. The result is a strip of paper with a squiggly line. The rest is up to the human eye and brain.

On the afternoon of the first day, Kradz showed us what to look for. The unstressed voice looks like an untrimmed hedge, with stalks of different heights sticking up (and down) at irregular intervals. But add some stress, and that hedge begins to look trimmed. The greater the stress, the

## The more I read, the more I doubted the official account of what happened that day in Dallas

smoother the shape. If the subject was experiencing the hard stress which accompanies deception, the over-all outline of the figure tends to take on a rectangular shape, a concertina as seen by the player. Kradz showed slide after slide of charts made during actual police interrogations. He told us the background of each case and pointed out the tell-tale signs of deception, whenever they were present.

That night each student took a PSE back to his room to practice operating it. Some coordination must be learned to become facile in handling the recorder and the PSE, but clearly the difficult part of the course would be learning how to read and interpret the charts.

the PSE. There is, first of all, the matter of the "outside issue."

The next day we learned the theory of

Most people, Kradz pointed out, have some sort of deep secret they don't want known. When faced with a polygraph examination, a person may be more concerned that this outside issue may come to light than he is about the actual substance of the interrogation. This can produce irrelevant stress in some of his answers, and mislead the examiner. Therefore it is necessary for the examiner to interview the subject before the examination, go over all of the questions he intends to ask, and assure the subject he will ask only these questions. I had reason to remember this later, when I ran my first real interrogation tape.

The interrogation always includes the question. "Are you afraid that I will ask you about something we have not discussed?" A negative answer with no sign of stress eliminates the outside-issue problem. Also, the examiner always asks some innocuous questions, such as, "Do you like the color blue?" in order to observe the subject's general state of tension. And there is always one "red-herring" question.

The red herring is used to identify the "guilt complex responder." Such a person shows stress when he responds to any accusatory question. The examiner may ask, "Did you steal the watch?" when it is money, not a watch, that is missing. A stressed denial will alert the examiner, who carefully compares this response to the stress produced by questions about the missing money.

That night the class was given tapes of real police interrogations. In most cases, Kradz was the examiner, and in every case, he knew the background and resolution of the matter. One case I was assigned concerned a young man accused of stealing money from his father's store. Kradz started by asking the "outside-issue" question. No, the young man replied, he was not afraid Kradz would ask him a question they hadn't discussed. Then the following exchange took place:

"Do you live in Howard County?" "Yes."

"Do you suspect someone of having taken the money?"

"No."

"Are you wearing a white shirt?" "Yes."

"Do you know who took the money?" "No."

"Are you wearing a ring?" "Yes."

"Did you take the money?" "No."

There were a few red-herring questions to check for the guilt complex response. The questions about wearing a white shirt and a ring and living in Howard County had been included to measure the background stress elicited by irrelevant issues.

I ran the tape and charted it on the PSE. All but two of his responses were unstressed. The question about suspecting