THIS EVALUATION IS UNDERTAKEN TO DEMONSTRATE THE VALIDITY OF TWO HYPOTHESES: (1) MANY ACTIVITIES OF INVESTIGATORS CONTRIBUTE LITTLE TO THE CLEARANCE OF CRIMES; AND (2) SOME CHARACTERISTICS OF CRIME ITSELF, OR OF EVENTS SURROUNDING THE CRIME THAT ARE BEYOND THE CONTROL OF INVESTIGATORS, DETERMINE WHETHER IT WILL BE CLEARED IN MOST INSTANCES. IT IS ARGUES THAT, BASICALLY, SOME CRIMES ARE EASY TO CLEAR, WITH EITHER NO WORK BY AN INVESTIGATOR OR WITH SMALL AMOUNTS OF ADMINISTRATIVE ROUTINE. THE REMAINING CRIMES, WHICH CONSTITUTE THE MAJORITY, ARE DIFFICULT TO CLEAR REGARDLESS OF THE EFFORTS EXPENDED BY THE POLICE. FURTHER, THE NUMBER OF DIFFICULT CRIMES THAT ARE EVENTUALLY CLEARED IS SO SMALL THAT WHEN COMPARED WITH THE CLEARANCE RATES FOR EASY OFFENSES, IT BECOMES APPARENT THAT THE OVERALL CLEARANCE RATE IS NOT MUCH AFFECTED BY THE INCREASED INVESTIGATORY ATTENTION DEVOTED TO THE MORE DIFFICULT CRIMES. DATA WERE COLLECTED FROM THE POLICE DEPARTMENT IN BERKELEY AND LOS ANGELES (CALIF.), MIAMI (FLA.), KANSAS CITY (MO.), AND WASHINGTON, D.C. FOR THE PURPOSE OF THE EVALUATION, CRIME DATA WERE DIVIDED INTO TWO LOTS: THOSE CRIMES IN WHICH AN INITIAL IDENTIFICATION OF THE PERPETRATOR(S) WAS MADE, AND THOSE CRIMES IN WHICH NO INITIAL IDENTIFICATION WAS MADE. IN CASES WITH AN INITIAL IDENTIFICATION, INVESTIGATOR INVOLVEMENT IN CASE CLEARANCE IS GENERALLY ROUTINE AND AT BEST MINIMAL. EITHER THE SUSPECT IS ALREADY APPREHENDED OR SOME CLERICAL EFFORT ON THE PART OF THE DETECTIVE IS NEEDED FOR APPREHENSION. TABULAR DISPLAYS NOTING DATA SOURCES BY CRIME TYPE, SUSPECT IDENTIFICATION IN CLEARED CASES BY LEVEL OF INVESTIGATIVE EFFORT, AND METHODS OF SOLUTION IN CASES WITH INITIAL IDENTIFICATION ARE PROVIDED. IN NONROUTINE CASES IN WHICH A SUSPECT IS NOT IDENTIFIED IN THE INITIAL CRIME REPORT SEVERAL TYPES OF EFFORT ARE INVOLVED IN THE CASE SOLUTION. DATA ARE EXAMINED REGARDING THE PRINCIPAL METHOD OF SOLUTION FOR CRIMES IN WHICH THERE IS NO INITIAL IDENTIFICATION OF THE PERPETRATOR(S). THE USE OF FINGERPRINTS, TIPS, MUG SHOTS AND LINEUPS, MODUS OPERANDI, UNRELATED INTERROGATION, SPECIAL ACTION, AND THE ROLE OF SPONTANEOUS SOLUTIONS ARE ASSESSED IN RELATION TO THE CLEARANCE OF SPECIFIC CRIMES, INCLUDING FORGERY, FRAUD, AUTO THEFT, THEFT, COMMERCIAL BURGLARY, RESIDENTIAL BURGLARY, ROBBERY, FELONY MORALS, AGGRAVATED ASSAULT, AND HOMICIDE. THE DATA SUGGEST THAT WHEN THERE IS NOT INITIAL IDENTIFICATION OF THE SUSPECT(S), MOST CASES ARE SOLVED EITHER BECAUSE THE SOLUTION IS OBVIOUS OR BECAUSE THE DEPARTMENT HAS DEVELOPED PROCEDURES THAT HAVE 'ROUTINIZED' METHODS OF SUSPECT IDENTIFICATION. THE DATA FROM KANSAS CITY ARE DISCUSSED IN PARTICULAR REGARDING THE METHODS OF CLEARANCE FOR CRIMES TYPICAL OF THE ABOVE. TABULAR BREAKDOWNS ARE PROVIDED REGARDING THE LEVEL OF INVESTIGATOR EFFECT, SPECIAL ACTION CASES, AND THE METHOD OF SOLUTION FOR CLEARED CASES. IT IS CONCLUDED THAT IN MORE THAN HALF OF THE CLEARED CASES, THE IDENTIFICATION OF THE OFFENDER IS AVAILABLE AT THE TIME OF REPORTING, AND MOST REMAINING CASES THAT ARE EVENTUALLY CLEARED ARE SOLVED THROUGH SIMPLE, ROUTINE ACTIONS. (KBL)