How to Perform a Ninhydrin Test to find Latent Prints

Ninydrin is an amino acid-developing agent that can be applied by dipping, brushing or spraying. The Ninhydrin test can be used in forensics to discover latent prints and is especially useful for finding latent fingerprints 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
• porous item with print on it

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 will work for fingerprint lifting.

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

4. Heat the chamber to 80 degrees Celcius.

5. Set the humidity between 40% and 60%. The heat and humidity will catalyze finger print development.

6. Photograph the fingerprint through a green colored filter. This will more accurately pick up the latent prints that develop through the Ninhydrin test.

7. View this photo under a forensic light at 530nm to determine if the latent fingerprints are of value.

Tips & Warnings

• Ninhydrin is an irritant if inhaled or if it comes in contact with your skin.

Resources

• Lift fingerprints from non-porous surfaces
• Traditional fingerprint dusting