Fingerprints on the plastic surface have more ridge details when compared to porous surfaces such as fingerprints on clothes. However, as the nature of plastic is a non-porous substrate, the chance of finding finger marks is less as compared to semi-porous surfaces such as fingerprints on paper.
Latent fingerprints on plastic surfaces can be developed for up to 5 years. On rigid plastic, the finger marks can last for 5 years if remain undisturbed (or even more). In flexible plastic surfaces, they can be developed up to a few weeks to a few months. For blood fingerprints on plastic, development depends highly on environmental conditions.
| Plastic Materials | Time Fingerprint Rest* |
|---|---|
| Plastic bottle | 6 months |
| Food Packaging Film | 3 months |
| Plastic Plates and Cups | Few years |
| Window Panels | 5-6 Months |
| Toys | 1-12 months |
| Plastic File Covers | 1 year |
| Pen | 2-4 weeks |
| Knife handle | 1-2 months |
| Cookware handle | 1-2 months |
| Credit and Debit Cards | 3 months |
| Pipes (PVC) | 1 year |
| Cable Insulations | 1-2 weeks |
| Black Garbage bag | 3-6 months |
| Adhesive Tapes (Non-sticky side) | 1 month |
| Tape Cassettes | 1 year |
| Electrical Appliances | 1-5 year |
| Slippers and Flops | 2-4 weeks |
When You Find Fingerprints on Plastic? And When Not?
The presence or absence of fingerprints on any surface depends on various factors as follows:
A. The environment in which the fingerprint is being taken
Environment plays a very important role in the preservation of fingerprints. Contamination of prints with soot gets deteriorated very soon. However, prints contaminated with blood, pigments, ink, etc are more resistant to deterioration.
Joseph De Alcaraz et al. determined various factors related to fingerprint degradation on surfaces (glass and plastic) over 6 months.
B. The surface containing the fingerprint
For plastic, the substrate can be plastic which can be categorized in terms of
(i) Porosity: Usually non-porous and rarely semi-porous. Porous is usually not found with the plastic substrate.
- Non-Porous substrate: most plastic
- Semi-porous substrate: creative sheets and some plastic papers (check developing prints on paper).
(ii) Rigidity: Plastic can be rigid or soft/flexible. The rigid plastic surface tends to retain fingerprints longer than flexible and soft plastics.
C. Age of the fingerprint
The age of the fingerprint is the difference between the time of deposition and collection. Cadd et al. explore the various donor composition characteristics along with the kinetics of variations for getting fingerprints.
How to Find Fingerprints on Plastic?
Common Visual Remedies for finding fingerprints:
- Visible Prints: Fingerprints stained using dyes, pigments, blood, grease, etc. are visible to the naked eye. Hence, they can be identified as such.
- Latent (hidden) Prints: can be found using:
- Bright light at oblique angles
- Alternate light sources, and captured using camera filters
- Laser, UV, and IR Spectrum
Ways of Developing Fingerprints on Plastic
There are various ways of fingerprint detection and identification (as per various manuals of Forensic Agencies) as follows:
- Powders: Various magnetic powders and non-magnetic powders are used for the development of fingerprints. Eg. Black fingerprint (Ferric Oxide powder, Lampblack powder), White fingerprint (TiO2 powder, Chalk), Grey fingerprint (Lead Carbonate powder), and Luminescent powders.
- Iodine fuming: A universal technique for the development of fingerprints.
- Cyanoacrylate fuming
- DFO (1,8-Difluoren-9-one) gives fluorescence
- Vacuum Metal Deposition (VMD)
| Plastic Surface | Example | Fingerprint Deposition | Developing Agents |
|---|---|---|---|
| Dark Color Plastic | Any plastic substrate | Latent | White powder, Cyanoacrylate fuming (CAF) |
| Dark Color Plastic | Any plastic substrate | Blood | Acid Yellow 7, Cyanoacrylate fuming (CAF) |
| Light Color Plastic | Any plastic substrate | Latent | Black powder |
| Light Color Plastic | Any plastic substrate | Blood | Amido Black or Acid Violet 17 |
| Rigid Plastic | PVC, Plastic containers, etc. | Latent | Cyanoacrylate fuming (CAF), Powder |
| Rigid Plastic | PVC, Plastic containers, etc. | Blood | Amido black, Acid Yellow 7, Superglue method |
| Flexible Plastic | Plastic garbage bags & other polythene | Latent | Supeglue, Amido black |
| Flexible Plastic | Plastic bags & other polythene | Blood | VMD, Powder, Amido black, Acid Violet 17 |
Research Data: The fingerprint development technique used. Sarah J Fieldhouse observed the effectiveness of Cyanoacrylate fuming on textured and smooth plastic surfaces while aluminum powder was effective on the glass surface.
Can You Lift a Fingerprint From a Plastic Surface? When and When not?
Yes, fingerprints can be lifted from most plastic surfaces. The ability to lift a fingerprint from a plastic surface depends on the following factors:
1. Surface Uniformity: If the surface is smooth, the fingerprint developed can be easily lifted after development. However, the damage to the surface (scratches, pits, holes) will restrict a clear print. Hence, partial prints will be lifted from such surfaces.
2. Porosity of surface: The more porous surface will have difficulty in lifting as the fingerprints have more seeped through pores.
3. Thickness of Plastic surface: Surfaces such as wood wrap plastic are so thin that lifting might damage the surface and fingerprint. Hence, thin layered plastic makes it difficult to lift fingerprints.
Is it Possible to Extract DNA from Fingerprints on Plastic? And how long?
Yes, DNA can be extracted from fingerprints on plastic. According to a study by Lana Ostojic et al., a full DNA profile can be obtained even after 40 days from fingerprints. However, after a certain time, it may not be sufficient for DNA typing and identification.
However, the extent of recovery is attributed to several other factors as follows:
1. Pre-Development vs Post-Development: Robin Parsons et.al. a study on the recovery of DNA on various surfaces before development to determine the extent of recovery and damage to both ridge details and DNA. The team compared various lifting techniques on various surfaces and their effects on getting DNA.
2. Shredder Status: The experiments of Lowe et al. showed that the amount of DNA left on an object by touching it presents an inter-individual variability that allows subjects to be grouped as good or poor shedders.
3. Best method for DNA recovery from a Fingerprint: According to a study conducted by Sarah Fieldhouse, flocked swabs and gel lifts were the least destructive DNA recovery technique.
References:
- Fingerprint composition and aging: A literature review by Cadd, S., et al. (2015). [ScienceDirect]
- Latent Fingermark Aging Patterns (Part III): Discontinuity Index as One Indicator of Degradation by De Alcaraz-Fossoul, J., et al. (2017) [NCBI]
- Determination of latent fingerprint degradation patterns—a real fieldwork study. De Alcaraz-Fossoul, J., et al. (2012). [Link]
- Evaluation of latent fingermark color contrast as aging parameter under different environmental conditions: A preliminary study. De Alcaraz‐Fossoul, J., et al. (2020). [Wiley]
- The effect of DNA recovery on the subsequent quality of latent fingermarks. Fieldhouse, S., et al. (2016). [ScienceDirect]
- An Investigation into the Use of a Portable Cyanoacrylate Fuming System (SUPERfume®)….. by Fieldhouse, S. J. (2011). [Researchgate]
- Analysis of fingerprint samples, testing various conditions, for forensic DNA identification. Ostojic, L. and E. Wurmbach (2017). [Pubmed]
FR Author Group at ForensicReader is a team of Forensic experts and scholars having B.Sc, M.Sc, or Doctorate( Ph.D.) degrees in Forensic Science. We published on topics on fingerprints, questioned documents, forensic medicine, toxicology, physical evidence, and related case studies. Know More.