The persistence of ligature marks: towards a new protocol for victims of abuse and torture.

One of the most frequently observed lesions in clinical forensic practice concerns the patterned abrasion on skin due to constriction by various types of ligature. Detection of ligature marks and their patterns may be fundamental for reconstructing events and supporting testimony of an aggression, sexual abuse, or maltreatment. But very little actually exists in literature concerning their detectability and how long they last. This study aims at evaluating the time of persistence and detectability of skin signs left by different types of ligatures in living persons: on the arms of three volunteers, eight different ligatures were applied; 123 tests were performed, with time of contact ranging between 1 min and 2 h and 45 min. In addition, the persistence of the shape and pattern of the ligature was evaluated 15, 30, and 60 min after a 5- and 15-min compression. Polyvinyl siloxane, applied by a gun dispenser, was used to perform a cast of the skin mark. The results show that the pattern was less distinguishable with the decrease of time of contact, going from 75 % after 10 and 15 min of contact, to 45.8 % after 1 min. Above 15 min, the specific pattern was always recognizable. In addition, a progressive decrease of the detectability of the pattern with time, respectively, up to 12.5 and 37.5 % in 5- and 15-min tests was observed. This study provides useful results for the assessment of patterned injuries in forensic pathology and clinical forensic medicine, both on dead and living persons: in addition, the use of silicone casts seems to be a reliable and cheap method for easily recording and preserving the morphological profile of skin lesions.