Twelve latent fingerprint examiners participated in a collaborative study of a modification of the official first action powder brushing method for the development of latent fingerprints. Latent images were placed on glass slides by the examiners, using male and femal subjects. The standard brushing method, using black, copper, and gray powders provided by the Associate Referee, was used to develop the fingerprints at various times up to 120 hr after the images were placed on the slides. Conclusive results were obtained: 139 of the 160 images (86.9%) were considered suitable for identification purposes. The method has been adopted as official final action.