SCIENCE WARS ON CRIME

Auckland Star, Volume LXIX, Issue 280, 26 November 1938, Page 9 (Supplement)

SCIENCE WARS ON CRIME

The G-Men's Invisible Rays

ByRex Collier

No. XI. —Copyright INVISIBLE rays that render I invisible objects visible are ri ft of the stock-in-trade of J. I.rl :r .tr Hoover's practitioners of t lie modern art of crime detection. C-miMi, in popkinrr to throw lijrlit on n ciiino mystery, sometimes lirefor to work m the (lurk. The light they throw in tin I'vcMiliinlity „ ia y lm f |, o 90 . ctl n Pt | Muck lurlit, ol t}l l- ultra-violet, iny arc it tho in frit, rod ray of cxree<lin K ]'y low' I 11 1.■ 'i.. in- the penotrfitin-r X-rny at 'i' <" ''iiil of tlio wave sc;tlr>.

, 1 I Iturcmi of Investigation li'is ,aK '' ll ml \ m lit m iri> of tho principles 'm luil him in tin* examination of iiuuiv I V pes of eviileilee in . I iin imm 1 eases. Theso I 'lie in mi enii long lni \« been known to 1 ""il'l of science, of course, but it I-. only in recent, years that their value m riiini* i ii\ est ions luia been widely M'c«>trn i^ed.

llt i'm ■ \ inlet, 1 i*_r 111. which consists of i.ivm of lip li fi'c.|u<Micy beyond tho wave i iiiltc > ot \i-ili|i> violet, is of importance I'vniiso it lum iho power of exciting ccri mi iiiit i"i i,i U to omit visible radiations

"i \:iii-il hues. Physicists call thw !111 °11<11111>11<111 lluorcsccncc.

(•iiwlmiil, research lins c|nnlifled F.R.I. I ''I'll n iein ns to idnntlf.v and catalogue '"■my sub-tunces according to thpir fl'uo-

properties. Nome materials iluorp«'MH» more than others, and sonic liko the (li.ininnd—cannot ho depended upon to react tho same under all condi-

A Tribute •Dear Mr. Collier: •I want to express my aopreelation for the splendid manner In •hich you have handled this most important phase of our work.. "The many years which you hove spent In studying law enforcement problems, and in particular the far-riung activities of the Federal Bureau of Investigation, qualify you particularly to write upon the scientific phases of our work in on *uthoritative manner. 1 *1 am confident the Art!— ' clea will prove most interesting to ' readers, as well as be of marked as. 1 31 stance to law enforcement gener- < ally, by pointing out the rapid advances that have been made and the fact that criminals no longer can •scape det«4tion and apprehension as oasUy as they could in tho past.* (Signed) J. EDGAR HOOVE** turn*. For that reason the laboratory men have conducted much ex[«Mimentati"n to familiarise themselves with the characteristics of countless substances. I bey are prepared to assert when a finding is positive and when a rciiort must be ((iinlified.

It is not always essential that a innterial lie absolutely identified, however. I-or example, the uncanny ability of ultra-violet light to expose erasures not, otherwise apparent to the eye has been of distinct service to F.B.T. docunieut examiners, as mentioned in a previous article. Any disturbance or removal of the sizing on the paper can bo detected readily with "black light," due to the difference in fluorescence between tho altered spot and the surrounding paper. Occasionally, If the erasure is superficial, tho original writing may be deciphered under the light.

Secret writing with invisible ink lo«cs its secrecy in the radiations of the ultra-violet carbon or mercury arcs used

This is one of a series of articles showing horo the Federal Bureau of Investigation has developed highly scientific methods in its Jvar on crime, and here reveals for the first time just how these Government experts are Wording to protect life and property. These are aut entic articles based on actual F. 8.1, cases and have been read and approved by ]. Edgar Hoover.

in the F.B.T. laboratory. Messages written in lemon juice, saliva and a number »t other solutions have been developed between tlie lines ~f an apparently innocent letter mailed by prison plotters.

If an ink eradicator has been used in tampering with a bank ledger or similar record, the fluorescent potentialities of 1 lie original ink remain, for 11io eradieator lias not removed the ink—merely bleached it.

A ' ""'' " * '/ / \ ft"' ; '' '< • / - ; , • /fc/ «>• ■ ./A*?

Secrct writings are made visible by use of ultra-violet light, as shown in the above Idler. You c.m read what the light brought to the surface between the darker writing.

The F. 8.1, successfully employed the fluorescent principle in reading obliterated writing on a pilot's chart recovered from the wreckage of an aeroplane that crashed atop a mountain. The chart wai so badly stained with oil from the motor that the pilot's notations could iiot be read. In investigating the crack-up the Bui eau of Air Commerce asked assistance of the F. 8.1, laboratory in determining the wording of the pilot's memoranda.

Ihe pilot had used a lead penoil in making the notations. Under the rays of the ultra-violet lamp the graphite pai t ides left by the pencil fluoresced brightJy through the oil, clearly revealing the otherwise indistinguishable writing. The reconstruction of this memorandum was of help in determining the cause of the crash.

Jn a similar case infra-red rays were fried after ultra-violet light had failed, 'i his time the aeroplane log was covered with blond. A photograph of the record in the ]<>w-fre(|iieney light brought out thi> entries made by the pilot just before the accident.

The ultra-violet rav« have enabled laboratory technicians to discover and identify stains in certain criminal cases. While blood in its natural state cannot readily be identified In- "black light" examination, treatment with sulp.func aeid will produce a distinctive orangered fluorescence, which becomes a brilliant red when ammonia is added. Many other stains are highly luminescent under ultra-violet light!

As a preliminary testing agent for stains, "ultra-violet light has no equal. A suspect's clothing may be spread on a, table and examined quickly for spots that may prove significant. Usually the next step is to subject the stain to microscopic and-chemical analyses for linal classification.

Tho Bureau's identification with ultra- \ inlet light of stains on the wearing apparel of a man suspected of assaulting a 12-year-old girl in Columbia, Tennessee, prompted the defendant to plead guilty. Ho received a life sentence.

F.B.T. experts conducting researches with "black light" have found another valuable use for these rays. A picce of torn cloth may be matched with fabric from which it was ripped if there happens to be a fluorescent stain along the line of tear.

These expert® freely admit that ultraviolet light examination has its limitations. They have found the rays jinreliable in detecting latent fingerprints, in determining the age or com-* position of inks and in revealing several types of secret writing.

I'hntoarnphy with infra-red light also lifts it* limitations, they declare, but there arc times when this technique if almost indispensable.

A unique case which well illustrates tint possibilities of infra-red ray photography came to the F.B.T. laboratory reef' litly from the Smithsonian Institutions division of fine arts.

An old chromo lithograph had puzzled the institution's art curator. Its age and origin were matters of much conjecture. The canvas, showing as its central character a figure of Christ, was removed from its ancient frame, whereupon faint pencil notations could be seen. The traces of writing were too indistinct to be read, however. The F. 8.1, was asked if its laboratory staff could aid in unravelling the inscription. . Utilising special plates sensitive to infra-red light, the laboratory examiners

photographed the writing under infrared rays. The developed plate showed clearly the title, "Christ Blessing Bread," and part of the name of the artist, Carlo Dolci. With this information, the museum was able to list the picture its a copy of an original painting in the Dresden Art Galleries. The copy, officials said, was made by a rare process used between rS7O and 1880.

Infra-red photography has been utilised to good advantage in developing faded writing on old papers, registers and other documents.

The laboratory has complete X-ray equipment for the examination of packages suspected to contain bombs, and to search for metallic objects secreted in clothing, books or other hiding places.

Bombs often are constructed so that the detonating mechanism will function only when the box enclosing it is opened. Fluoroscopic examination of the package will show whether the contents are explosive and, if so, how the box may be opened without tripping the detonator.

Usually the suspected package is nothing more dangerous than a box of candy, an alarm clock that has started ticking ominously or some other harmless article.

A long, heavy package of sinister appearance came to a high Government official some time ago. His secretary did not like the looks of the thing, nor the sound of the weighty object inside when the package was shaken. It was decided to call in the G-men's bomb experts.

The suspicious package was photographed with X-ray apparatus and the "bomb ' was found to be a handsomely carved wooden gravel —gift to the official of an admirer in a far awav State.

The piercing eye of the X-ray machine ®aw through the leather sole of a convict s shoe and bared several hacksaw blades that had been smuggled into prison. The discovery possibly frustrated a prison break. Roentgen rays have no monopoly on metal detection.

A var»ant of this apparatus has been adopted by the Federal Prison Bureau to guard against smuggled guns, knives, saws and other articles which might be used in an escape conspiracy*. Doorways have been equipped with these electric metal detectors at Alcatraz Island Penitentiary, so that a signal is given guards when any one with a metallic object 011 his person passes the electrified portal. Every prisoner entering this Federal colony for incorrigible convicts is searched with the aid of the metal detector, and regular examinations are made thereafter.

Thus science not only is playing a part in putting the erimhial behind bars but is helping to keep him there.