EXAMPLES ILLUSTRATE THAT THE POLICE CANNOT LEAVE A JEWELRY STORE HOLDUP UNSOLVED BECAUSE AN ANONYMOUS LETTER NAMING THE ROBBERS WAS WRITTEN OUT OF PERSONAL HATRED FOR THE OFFENDERS RATHER THAN CONCERN FOR THE PUBLIC GOOD, AND THAT IGNORING BOMB THREATS BY TELEPHONE CAN LEAD TO LOSS OF LIFE AND PROPERTY DAMAGE. IN EACH INDIVIDUAL CASE THE POLICE MUST CAREFULLY CONSIDER THE SERIOUSNESS OF THE OFFENSE, THE URGENCY FOR ACTION, THE CREDIBILITY OF THE INFORMATION, AS WELL AS THE GENERAL BEHAVIOR OF THE ACCUSED PARTY, AND MUST ALSO ATTEMPT TO DETERMINE THE ACCURACY OF THE INFORMER'S INFORMATION OR ANY SLANDEROUS INTENTIONS WHICH HE MIGHT HARBOR. WHEN THE POLICE CHOOSE NOT TO PURSUE ANONYMOUS LETTERS FURTHER, THE ANONYMOUS TIPSTERS OFTEN WRITE AGAIN DEMANDING ACTION. POLICE MUST ALSO ATTEMPT TO ESTABLISH THE IDENTITY OF PERSONS WHO SEND THREATENING LETTERS OR HARASS HELPLESS INDIVIDUALS WITH ANONYMOUS TELEPHONE CALLS. WHEN SUCH CALLS OR LETTERS ARE PROMPTED BY VIOLENT EMOTIONAL REACTIONS, DISCOVERY OF THE MOTIVES CAN LEAD TO THE GUILTY INDIVIDUAL, BUT TRUE CRANKS CANNOT BE IDENTIFIED BECAUSE NO LOGICAL REASON FOR THEIR CHOICE OF VICTIMS IS APPARENT. ANONYMOUS LETTER WRITERS SOMETIMES WILL USE A FICTICIOUS NAME AND ADDRESS TO LEND CREDIBILITY TO THEIR STATEMENTS, EVEN THOUGH POLICE ARE LIKELY TO CHECK. THE NEED TO CONCENTRATE ON THE CONTENTS OF THE MESSAGE RATHER THAN THE AUTHOR'S IDENTITY IN THE CASE OF SERIOUS CRIMES IS EMPHASIZED. -IN FRENCH. (KMD)