THE COMMON IODINE FUMING METHOD FOR THE DEVELOPMENT OF LATENT FINGERPRINTS ON PAPER SUFFERS FROM SEVERAL DISADVANTAGES: THERE IS RAPID FADE OF THE IMPRESSION, PHOTOGRAPHY IS NOT ALWAYS SUCCESSFUL BECAUSE OF POOR CONTRAST, AND LATENT PRINTS MORE THAN 3-DAYS OLD (SOME STUDIES INDICATE A 1-DAY LIMIT) MAY NOT BE DEVELOPED. TWO DEVICES, A LABORATORY UNIT AND A FIELD WORK DEVICE, WERE DEVELOPED TO ADD CONTROLLED AMOUNTS OF WATER VAPOR TO THE IODINE FUMES. THEY WERE TESTED ON A COLLECTION OF MORE THAN 1,000 LATENT FINGERPRINTS ON VARIOUS TYPES OF PAPER AND FROM DONORS OF DIFFERENT AGES, OCCUPATIONS, AND COUNTRIES OF ORIGIN. THE SAMPLES WERE STORED AT ROOM TEMPERATURE IN DARK ENVELOPES AND WERE DEVELOPED AT TEMPERATURES FROM -70 TO 100 DEGREES C. THE WATER VAPOR DEFINITELY INCREASED THE SENSITIVITY OF THE IODINE TO LATENT PRINTS OF POOR DONORS, INCREASED THE QUALITY OF CONTRAST, AND SUCCESSFULLY DEVELOPED PRINTS UP TO 110-DAYS OLD. BEST RESULTS WERE ACHIEVED FOR WHITE STATIONERY PAPER AND CHECKS. LESS IMPRESSIVE RESULTS WERE OBTAINED ON CIGARETTE PACKAGES AND BROWN WRAPPING PAPER. POOR RESULTS WERE ACHIEVED FOR FILTER PAPER, NEWSPAPERS, AND PAPER MADE OF GLASS FIBERS. THE METHOD WAS SUCCESSFUL AT ALL DEVELOPMENT TEMPERATURES. THE ARTICLE HAS PHOTOGRAPHS OF BOTH THE APPARATUS AND THE DEVELOPED PRINTS, AS WELL AS REFERENCES. (GLR)