IN CONSIDERING THE SOURCE AND RELEVANCE OF CLOTHING OBTAINED FROM SUSPECTED PERSONS, TWO FACTORS WERE INVOLVED: THE MEANS BY WHICH SUSPECTS WERE SELECTED BY THE POLICE AND THE CHOICE OF CLOTHING FROM THE SUSPECTS. SNEAK THIEVES WERE THE MAIN SUSPECT GROUP IN THE FIRST INVESTIGATION. ALCOHOLICS, VAGRANTS, AND VIOLENT SEX DEVIANTS CONSTITUTED THE MAIN SUSPECT GROUP IN THE SECOND INVESTIGATION. ALL SUSPECTS GARMENTS WERE VISUALLY EXAMINED FOR BLOOD STAINS. SUSPICIOUS STAINS WERE ALSO TESTED USING THE KASTLE MEYER REAGENT TO DETECT STAINS NOT READILY APPARENT IN VISUAL EXAMINATION. WHEN SUFFICIENT BLOOD STAINING WAS PRESENT, A PRECIPITIN TEST WAS CARRIED OUT. IN TOTAL, 178 GARMENTS FROM 90 SUSPECTS HAD BLOOD STAINS. ONLY 14 PERCENT OF THE STAINS COULD BE DESCRIBED AS EXTENSIVE OR HEAVY. APPROXIMATELY 6.6 PERCENT OF THE CLOTHING EXAMINED IN THE TWO INVESTIGATION HAD BLOOD STAINS OF SUFFICIENT SIZE TO ATTEMPT GROUPING TESTS. THE NUMBER OF PEOPLE IN THE SECOND CASE WITH BLOOD ON THEIR CLOTHING OF A DIFFERENT GROUP THAN THEIR OWN WAS 3.2 PERCENT. DIFFICULTIES IN EVALUATING THE SIGNIFICANCE OF BLOOD STAINS ON CLOTHING, IN TERMS OF THEIR EVIDENCE VALUE, CAN BE MINIMIZED IF TWO SEPARATE AND UNRELATED INVESTIGATIONS ARE CONDUCTED AND THE RESULTS COMPARED. IF THE RELIABILITY OF EVALUATING BLOOD STAINS ON CLOTHING IS DEMONSTRATED, FORENSIC SCIENTISTS AND THE COURTS WILL HAVE A HIGHLY DIAGNOSTIC DEVICE AT THEIR DISPOSAL. SUPPORTING DATA AND REFERENCES ARE INCLUDED. (DEP)