Long-Lasting Lipsticks and Latent Prints
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April 2002 - Volume 4 - Number 2 |
Research and Technology
Long-Lasting Lipsticks and Latent Prints
Ana Castello
Biochemist
Mercedes Alvarez
Assistant Professor of Legal Medicine
Marcos Miquel
Assistant Professor of Legal Medicine
Fernando Verdu
Professor of Legal Medicine
Department of Legal Medicine
College of Medicine and Odontology
University of Valencia
Valencia, Spain
Abstract | Introduction | Materials and Methods | Results
Conclusions | References
The investigation of latent prints can be fundamental in resolving a criminal act. In addition to fingerprints, lipstick smears can be investigated. Traditional lipstick produces a print that is easily identifiable. However, lip prints made with long-lasting lipstick can be invisible, requiring reagents that are more sensitive than conventional materials to locate and develop the prints. This study analyzes the effectiveness of reagents that are generically called lysochromes (Sudan III, Oil Red O, and Sudan black) in developing recent as well as older latent lip prints on porous surfaces.
The investigation of latent prints can be fundamental in resolving a criminal act. There are different physical and chemical methods that enable locating and developing latent prints (Trozzi et al. 2001). It is also feasible to extract DNA from the print (Fregeau et al. 2000; Zamir et al. 2000).
In addition to fingerprints, lipstick prints can be of forensic interest. Lipstick smears can lead to indirect proof of a relationship or contact between a victim and a suspect or a suspect and a crime scene (Ehara and Marumo 1998). Also, the possibility of extracting DNA from saliva on a lipstick print may be valuable in an investigation.
Traditional lipstick produces a print that is initially easily identifiable (Lucus and Eijgelaar 1991; Russell and Welch 1984). However, the cosmetics industry has developed long-lasting lipsticks that often do not leave visible prints.
Different lipsticks have different compositions. During the manufacture of long-lasting lipstick, the oil content is reduced to a minimum. Thus, development using conventional powders and reagents is more difficult. Previous studies analyzed the effectiveness of several fingerprint powders and reagents on lipstick prints. Of these, fingerprint red (Dragon’s Red), fingerprint black, and silver metallic powders were found to be the most effective (Alvarez 1999; Seguí et al. 2000). It was also determined that sublimated iodine does not produce development. Thus, it is necessary to find other development methods that are more sensitive to oils and more easily applied.
Lysochrome is a generic term for compounds that have the ability to dye fatty acids (Budavari 1996; Lillie 1969). Their molecule contains a portion that dissolves in contact with fat (lyso) and another that is responsible for color (chrome). Their use is common in histopathology for determining fats in sections. One of these compounds, Sudan black, has been used as a solvent in ethanol and water to develop latent fingerprints described in the literature about surfaces contaminated with foodstuffs, oils, and other fatty substances (Trozzi et al. 2001).
This study compares the effectiveness of three different lysochromes (Sudan III, Oil Red O, and Sudan black) to the fingerprint red (Dragon’s Red), black, and silver metallic powders as well as to ninhydrin in developing latent lip prints from long-lasting lipsticks on porous paper and cloth surfaces. The reagents were used both in powder and in solution forms. Lysochromes have an advantage over a chemical reagent because they react with fats and physical reagents.
Materials:
Long-lasting lipstick
Unperfumed tissue paper
White cotton fabric
Bottles (dark storage, sprayer, plastic)
Brushes
Fume hood and fuming chamber
Glassware
Heater
Humidity chamber
Stirring device
Fingerprint Powders:
Fingerprint red powder (Dragon’s Red)
Fingerprint black powder
Silver metallic powder
Reagents:
Ninhydrin
Acetone
Sudan III
Oil Red O
Sudan black
Ethanol
Distilled water
Methods:
Sample preparation:
After applying the lipstick on ten volunteers and waiting the recommended five minutes for the lipstick to fix, lip impressions were made on tissue paper and white cotton fabric using sustained pressure for three seconds. The samples were exposed to ambient conditions.
Reagent preparation (Trozzi et al. 2001):
Ninhydrin (acetone base) for 100 ml:
Ninhydrin 0.6 g
Acetone 100 ml
The reagent was dissolved in acetone with minimal stirring.
Sudan III (solution) for 150 ml:
Sudan III 1.5 g
Ethanol 100 ml
Distilled water 50 ml
The reagent was dissolved in ethanol, water was added, and the mixture shaken.
Oil Red O (solution) for 150 ml:
Oil Red O 1.5 g
Ethanol 100 ml
Distilled water 50 ml
The reagent was dissolved in ethanol, water was added, and the mixture shaken.
Sudan black (solution) for 150 ml:
Sudan black 0.375 g
Ethanol 100 ml
Distilled water 50 ml
The reagent was dissolved in ethanol, water was added, and the mixture shaken.
Processing procedure:
The latent lip prints were developed at intervals ranging from 1 to 40 days. Two observers independently performed the readouts of the development. The protection measures recommended by the products’ Safety Data Sheets (Merck Schuchardt 1998) were followed. Some of the development procedures are demonstrated in Figures 1, 2, 3, and 4.
| Figure 1 Photograph of a latent lip print on cotton fabric developed using black powder after 30 days. Click for enlarged image. | Figure 2 Photograph of a latent lip print on cotton fabric developed using Oil Red O (powder) after 30 days. Click for enlarged image. |
| Figure 3 Photograph of a latent lip print on cotton fabric developed using Sudan black after 30 days. Click for enlarged image. | Figure 4 Photograph of a latent lip print on cotton fabric developed using Oil Red O (solution) after 30 days. Click for enlarged image. |
Developing with fingerprint powders (red, black, and silver metallic) and powder lysochromes (Sudan III, Sudan black, and Oil Red O): Using a brush, a small quantity of powder was carefully applied on the surface where the attempt was being made to locate the latent lip print. Enough of the background was developed to see the entire lip print. Application continued and extended until the print could be seen clearly. When using powder lysochromes, very little reagent was used, but sufficient time was provided to allow it to work. With time, the development became clearer, presenting a better quality image.
Developing with ninhydrin (acetone base): The reagent was applied to the sample using a spray, then allowed to dry.
Developing with solution lysochromes: With the reagent in a glass tray, the sample was submerged in the solution. When using Sudan III or Oil Red O, the sample was left submerged for approximately one minute, then removed. When using Sudan black, the sample was removed immediately to prevent the paper or fabric from becoming dyed. It was then rinsed with tap water and allowed to dry.
The quality of the development for the powders and reagents studied depends on two factors: the surface type and the age of the latent lip print.
- On tissue paper, neither recent nor older prints were developed using conventional fingerprint powders (red, black, and silver metallic). On the other hand, lysochromes (Sudan III, Oil Red O, and Sudan black) applied as a powder and in solution produced high quality development of prints up to 20 days old. The effectiveness of the development diminished with the age of the print, with poor quality on older prints.
- On white cotton fabric, both conventional powders and reagents were used to develop recent lipstick prints, but their effectiveness diminished on older prints. Silver metallic powder achieved the best results with high-quality development of prints up to 10 days old. Lysochromes produced good quality development of prints up to 40 days old. But on fabric as on paper, the effectiveness of the powder or reagent diminished over time, and the quality of the development was poorest on the oldest prints.
Analyzing the results obtained for the two surfaces, the quality of lip print development was better on fabric than on tissue paper, probably due to differences in the structure of these surfaces. The tissue paper’s softer surface allows the development process to affect the structure, producing poor results. Since it is more absorbent than fabric, the print adheres to the tissue paper better, thereby reducing the effectiveness of the powders and reagents. On the other hand, the structure of woven fabric is more homogeneous, more uniform, and firmer than that of paper. The components of the print do not adhere well to the fiber; thus, the powders and reagents become more effective. This explanation, however, is only hypothetical.
Tables 1 and 2 present the results of this study after developing latent lip prints produced by long-lasting lipsticks using different fingerprint powders and reagents after different dwell times. Table 1 shows the results on tissue paper; Table 2 shows the results on white cotton fabric.
The results obtained for conventional powders and reagents were compared to those derived from lysochromes, suggesting the following conclusions:
- Conventional powders and reagents are less effective than lysochromes in developing older lip prints. Moreover, results cannot be obtained on some porous surfaces, such as paper.
- Lysochromes applied either as a powder or in solution are effective on both types of porous surfaces tested. They achieve development of recent and older lip prints.
- Ninhydrin, which reacts with amino acids in perspiration to make it an effective reagent for developing latent fingerprints, provides no useful results for lip prints, since there are no sweat glands in the lips. The use of ninhydrin produced no reaction.
An analysis of the results for the three lysochromes (Sudan III, Oil Red O, and Sudan black) provided the following conclusions:
- Oil Red O and Sudan black in powder form produced high-quality developments for recent as well as older lip prints. Sudan III was less effective for older lip prints than the other two reagents.
- Sudan III and Oil Red O in solution produced good development (better with the latter) of recent and older lip prints. The results were excellent using Sudan black producing high-quality development of prints up to 40 days old. However, this reagent may dye the paper or fabric, preventing the print from being seen. To prevent this dyeing, the concentration of the reagent in the solution should be lowered, and the sample should be washed immediately after application.
- Lysochromes are effective in both powder and solution application forms. Of the three reagents used, the best results were with Sudan black, followed by Oil Red O and Sudan III.
This study shows that lysochromes are very effective when used on long-lasting lipstick prints on porous surfaces, such as paper or fabric, where detection is usually difficult. Thus, lysochromes are a highly useful group of compounds for locating and developing recent as well as older latent lip prints.
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