How to Perform the Ninhydrin Test to Find Latent Prints

Photograph latent fingerprints as they tend to fade quickly.

Ninhydrin is an amino acid developing agent that can be applied to surfaces by dipping, brushing or spraying. The Ninhydrin test is used in forensics to discover latent fingerprints and is especially useful for finding latent prints on porous surfaces such as paper, cardboard or unfinished wood surfaces.

Difficulty:

Challenging

Instructions

Things You'll Need

• protective clothing
• Ninhydrin
• Humidity chamber
• green filter camera
• forensic light

1. Put on protective clothing and a fume hood to prepare for the Ninhydrin test.

2. Dip, brush or spray the item with Ninhydrin; any of these methods work for fingerprint lifting.

3. Place the object with latent fingerprints on it into a humidity chamber.

4. Heat the chamber to 80 degrees Celsius.

5. Set the humidity between 40 and 60 percent. The heat and humidity catalyzes fingerprint development.

6. Photograph the fingerprint through a green-colored filter to accurately pick up the latent prints that develop through the Ninhydrin test.

7. View the photo under a forensic light to determine if the latent fingerprints are of value.

Tips & Warnings

• Ninhydrin is an irritant when inhaled or if it comes in contact with your skin. The proper protective clothing is critical to your well-being.

References

• Crime & Clues; Ninhydrin Processing; Pat A. Wertheim; September 2009

Resources

• Lightning Powder Company, Inc: Ninhydrin Technical Notes