Criminalystic: effectiveness of lysochromes on the developing of invisible lipstick-contaminated lipmarks on human skin. A preliminary study

Latent prints are an important evidence for identification. Nowadays, the technical means, the implementation of image processing techniques and the use of database makes it possible to detect and get information from some prints that seem to be useless at first sight. On the other hand, the possibility of using the print as a DNA source has to be considered, so as to double its identifying value. Human skin is a particularly difficult surface for developing this kind of evidences. Although different methods for locating and developing latent fingerprints on the skin have been already described, it has not been found any method, at the revised bibliography, to obtain and develop invisible lipmarks, that is, lipmarks from protective lipstick, or permanent or long-lasting lipstick. The aim of the work that follows is to determine the effectiveness of several reagents for developing invisible lipmarks on the corpses' skin. Preliminary results show that, under the described experimental conditions, the reagents used, Sudan III, Oil Red O and Sudan Black, are effective for obtaining recent latent lip prints on corpse's skin.     

Solid-phase microextraction for the determination of cocaine and cocaethylene in human hair by gas chromatography-mass spectrometry

A method for the simultaneous determination of cocaine (COC) and cocaethylene (CE) in human hair was developed, using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) as analytical technique to identify and quantify the drugs. Selected ion monitoring (SIM) mode was used to obtain higher sensitivity. The deuterated-labeled analogues were used as internal standards. The detector response was linear for the drugs studied over the range 0.4-15 ng/mg, with correlation coefficients higher than 0.995. The coefficients of variation oscillated between 0.65% and 14.18% and the accuracy was in the range from 0.73% to 11.20%. The limits of quantitation and detection were found to be acceptable. Finally, this method was applied to 15 hair samples from cocaine users, obtaining positive results in all cases. The mean concentrations were 5.39 ng/mg (range: 0.43-8.98 ng/mg) for cocaine and 1.11 ng/mg (range: 0.42-2.23 ng/mg) for cocaethylene.