Nikoui and Associates, Forensic Identification Services & Consulting, LLC Logo

Unlocking Hidden Clues: 1,2-Indanedione as a Cutting-Edge Fingerprint Developer

07/23/2024
Fingerprints Tape Measure

by Kourosh Nikoui | Jul 23, 2023 | Fingerprint Processing

In the world of forensic science, the ability to recover latent fingerprints from crime scenes is crucial. These hidden prints, often left behind on various surfaces, can serve as pivotal evidence in criminal investigations. While numerous methods exist to develop these prints, 1,2-Indanedione has emerged as a groundbreaking reagent, particularly for use on porous surfaces like paper. This blog will explore the application of 1,2-Indanedione in fingerprint recovery, compare it with the traditional reagent ninhydrin, and discuss its advantages and limitations.

What is 1,2-Indanedione?

1,2-Indanedione is a chemical reagent used in forensic science for developing latent fingerprints. When applied to porous surfaces, it reacts with amino acids present in fingerprint residues, producing a fluorescent compound that can be visualized under specific lighting conditions. This characteristic makes 1,2-Indanedione particularly effective for revealing prints that might otherwise remain invisible to the naked eye.

Application and Mechanism

1,2-Indanedione is typically dissolved in a solvent such as ethanol or acetone. However, for enhanced performance and safety, it is often mixed in 3M HFE-7100, a hydrofluoroether solvent. This solvent is preferred due to its excellent solvency, non-flammability, and low toxicity, making the application process safer and more efficient.

The application involves:

  1. Dissolving 1,2-Indanedione in 3M HFE-7100 solvent.
  2. Applying the solution to the surface via dipping, spraying, or brushing.
  3. Allowing the treated surface to dry.
  4. Heating the treated surface to enhance the reaction, typically using an oven or a heat press.
  5. Visualizing the developed fingerprints under a forensic light source, usually in the green light spectrum, causing the indanedione-treated fingerprints to fluoresce.

Advantages of Using HFE-7100

One of the significant advantages of using HFE-7100 as the solvent for 1,2-Indanedione is that it does not cause ink to run or bleed. This property is particularly beneficial when processing documents that contain handwritten notes, printed text, or other ink-based markings. Preserving the integrity of such documents is crucial, as they may contain valuable contextual information or additional evidence.

Comparison with Ninhydrin

Ninhydrin has been the gold standard in latent fingerprint development on porous surfaces for decades. It reacts with amino acids to produce a deep purple color, known as Ruhemann’s purple, making prints visible. However, while both ninhydrin and 1,2-Indanedione target amino acids in fingerprint residues, there are notable differences between the two reagents:

Sensitivity:

  • 1,2-Indanedione: Generally considered more sensitive than ninhydrin, allowing for the detection of weaker or older prints.
  • Ninhydrin: Effective but may miss fainter prints that 1,2-Indanedione could reveal.

Visualization:

  • 1,2-Indanedione: Produces fluorescent prints, which can be more easily detected and photographed under appropriate lighting conditions.
  • Ninhydrin: Develops prints in a visible purple color, which can be seen without specialized lighting but may be less distinct on certain backgrounds.

Processing Time:

  • 1,2-Indanedione: Often requires heating and the use of a forensic light source for optimal results, potentially adding to processing time.
  • Ninhydrin: Typically develops at room temperature, though heating can speed up the process.

Sequential Processing:

  • 1,2-Indanedione: Can be used in conjunction with ninhydrin in sequential processing. Applying 1,2-Indanedione first can reveal prints that might be further enhanced with ninhydrin.
  • Ninhydrin: Can be used after 1,2-Indanedione to potentially reveal additional detail, but once applied, it limits further chemical treatments.

Advantages of 1,2-Indanedione

Higher Sensitivity: Capable of detecting weaker fingerprints, which is crucial for older or more degraded samples.
Enhanced Visualization: Fluorescence under a forensic light source often provides clearer and more detailed prints.
Safer Solvent: The use of 3M HFE-7100 makes the application process safer and more environmentally friendly.
Ink Preservation: Does not cause ink to run or bleed, preserving the integrity of documents with handwritten or printed text.
Sequential Processing Compatibility: Can be used as a precursor to other methods, enhancing overall fingerprint recovery efficiency.

Limitations of 1,2-Indanedione

Specialized Equipment: Requires access to a forensic light source and sometimes additional photographic equipment for optimal visualization.
Complexity: The application process can be more involved, needing precise control of conditions like temperature and light.
Cost: Generally more expensive than ninhydrin, which might be a consideration for budget-conscious forensic labs.

Conclusion

1,2-Indanedione stands out as a powerful tool in the latent print examiner’s arsenal for developing latent fingerprints on porous surfaces. Its ability to reveal faint and detailed prints through fluorescence offers a significant advantage over traditional methods like ninhydrin. The use of 3M HFE-7100 as a solvent enhances its safety and efficiency, while also preserving the integrity of documents by preventing ink from running. However, its need for specialized equipment and potentially higher costs means that it is often used in combination with other techniques to maximize effectiveness. By integrating 1,2-Indanedione into sequential processing protocols, latent print examiners and fingerprint analysts can unlock hidden clues that might otherwise go undetected, thereby enhancing the overall capability of criminal investigations.

Understanding the advancements in fingerprint analysis, including the application of 1,2-Indanedione, is essential for forensic specialists, crime scene investigators, and forensic investigators. These professionals continually seek innovative methods to improve the accuracy and reliability of fingerprint recovery, ensuring justice is served by uncovering the hidden truths embedded in every unique print.

Forensic Practitioner and Specialist Kourosh Nikoui, Principal Consultant and CEO of Nikoui & Associates, Forensic Identification Services & Consulting, Inc., has over 38 years of full-time experience in forensic science and criminal justice with various law enforcement agencies, government and private entities. Mr. Nikoui, a court-qualified expert, is a Certified Latent Print Examiner, Certified Senior Crime Scene Analyst, and Certified Forensic Photographer by the International Association for Identification. He has testified as an expert witness over 150 times in California Superior and U.S. Federal Courts, processed evidence in over 30,000 criminal and civilian cases, and served as a consultant to numerous law enforcement agencies. Mr. Nikoui holds a BFA degree from USD and is an active member of multiple forensic science organizations. He can be reached directly by calling (866)439-6753 or by email at [email protected]

References and Sources

  1. Almog, J., Sasson, Y., & Anati, L. (1999). 1,2-Indanedione: A New Reagent for Visualizing Latent Fingermarks on Paper—A Preliminary Report. Journal of Forensic Sciences, 44(2), 330-333.
  2. Lennard, C. (2001). The Detection and Enhancement of Latent Fingerprints. Forensic Science Communications, 3(2).
  3. Wilkinson, D. A., & Watling, R. J. (2006). Sequential Processing of Latent Fingerprints on Paper Using 1,2-Indanedione and Ninhydrin. Forensic Science International, 158(1), 14-20.
  4. Schwarz, L., & Bomford, C. (2006). A Comparison of 1,2-Indanedione and Ninhydrin for the Development of Latent Fingerprints on Paper. Journal of Forensic Identification, 56(4), 533-541.
  5. United States Department of Justice. (2000). The Use of 1,2-Indanedione and Ninhydrin for Developing Latent Fingerprints. Forensic Science Communications, 2(2).
  6. 3M Company. (2024). 3M™ Novec™ Engineered Fluid HFE-7100. Retrieved from 3M Product Information.
Forensic Identification Services & Consulting, LLC
Nikoui and Associates, Forensic Identification Services & Consulting, LLC |
37600 Central Ct Suite 205, Newark, CA 94560
|866-IDWORLD