SCIENTIFIC DETECTION OF CRIME — SANNIE 339 



centuries; the first consists of obtaining evidence from human wit- 

 nesses, and the second of obtaining evidence by studying the facts. 



Human testimony is obtained by examining the accused or witnesses ; 

 this is essential to any investigation, and explains why it is necessary 

 to be a good psychologist in order to be a successful investigator. 

 The report of the examination remains the cornerstone of the pre- 

 liminary investigation; many writers have explained how it should 

 be drawn up, and have worked out a set of rules, but they have also 

 drawn attention to its shortcomings. 



Evidence obtained from human witnesses has already been suf- 

 ficiently criticized.^ To seek for the truth in statements made by an 

 accused person who cannot speak the truth without condemning him- 

 self is hazardous, to say the least. The same is true of the evidence 

 given by his relatives, his children, or his servants ; it is so true that 

 it is forbidden by law to put them on oath before examining them. 

 Although "the right to lie" may appear open to criticism, it is never- 

 theless a fact which has to be accepted, and the probative value of 

 such statements is always very slight, or even nonexistent. 



The same is true, though to a lesser extent, of most evidence given 

 by human witnesses. Even a witness involved only by chance in a 

 crime, and having nothing to gain by lying, may make mistakes, and 

 often does. There are classical examples of the unreliability of mem- 

 ory, even in the case of recent events, showing how several people, all 

 acting in good faith, may remember the same series of events differ- 

 ently. A witness's physical or mental condition may influence him 

 without his being conscious of it, so that he sometimes distorts the 

 facts beyond recognition. In addition, it is not unusual for an inves- 

 tigator to suggest untruthful replies by the manner in which he puts 

 his questions. That is the danger of examining witnesses by means 

 of leading questions, and such interrogations have been responsible for 

 a great many false admissions. 



The proof that an investigator is most anxious to obtain is the 

 "final proof," that is to say, confession. With the inquisitorial system, 

 if suspects refused to confess, the police used to resort to torture, 

 although, as La Bruyere said : "It is a method calculated to lead an 

 innocent man, of weak resistance, to the gallows and to enable a guilty 

 man, with a strong constitution, to escape justice." 



When public indignation led to the abolition of torture at the end 

 of the eighteenth century, the only other known probative method was 

 interrogation or examination. 



' Any reader interested in this subject would do well to refer to L'Appr^ciation 

 des Preuves en Justice, by F. Gorphe, Paris, 1947, which is a classic, and to the 

 report presented by Dr. M. C6nac to the Fifty-ninth Congress of Mental 

 Specialists in 1951. 



