Fingerprints on Plant Leaves: How to Find and Develop them?

Plant’s leaves are not a common surface for finding fingerprints. However, the chance of developing prints on a leaf is much higher than that on clothes.

Key Notes:

• Possibility of developing fingerprints on leave surface.
• Even 1-month-old fingerprints can be developed on leaves.
• Bigger and broader leaves have good quality prints because of smooth and less vein surface.
• Dead leaves can also be a source of fingerprints.
• Best methods to develop fingerprints.

Possibility of Finding Fingerprints on Leaves

Fingerprints can be easily deposited on a leaf of a plant with regular touch. A study shows that it is possible to develop fingermarks on nearly all types of plant leaves including smaller, broader, or even dead leaves. And fingerprints on leaves can be found for up to 1 month.

Types of Prints: As they have no hard base when a finger touches the surface it pushes the leaves back which usually led to a partial print or a circular print.

Which Type of Surface are leaves?

The surface of leaves is non-porous due to the presence of plant cuticles, which is a hydrophobic layer (waxy coating) covering the entire plant. It prevents the loss of water through the surface of the plant body. The leaf surfaces also can be smooth, rough, wrinkled, or hairy. 

How Plant surface affects Prints development?

1. Plants that have smoother leaves with fewer veins are easier to develop and lift prints. 
2. Plants that have more veins made it difficult to get full prints as some ridge details are on the veins.
3. Leaves which have more waxy coating are easy to develop fingerprints. 

Fingerprints on Abaxial vs Adaxial Surface of a Leaf

In mature leaves, the adaxial surface corresponds to the upper side of the leaves, and the lower side of the leaf is known as the abaxial surface. 

Why Adaxial (Upper surface) side of the leaf have better Prints development?

• The upper side is greener and is more smooth than the lower side.
• The veins on the upper side are less protruding giving nearly a uniform surface, especially in indoor plant leaves.
• So, the development of latent fingerprints becomes easy on the adaxial (upper side) of the leave then on the abaxial prints.

Fingerprints on Dead leaves vs Live Leaves 

It is possible to develop and lift fingerprints even after dead plant leaves. Research conducted by Sundus and Albanese successfully developed fingerprints on dead leaves for up to 13 days.

Some challenges while developing prints on dead leaves:

• Leaves become brittle as they died in dry conditions making them sensitive to physical touch.
• The broader leaf surface becomes constricted to a smaller area.
• Easily gets damaged by water and the pressure of the fingerprint brush.
• Harder to lift fingerprints using the taping method, and casting can be done.

Methods for Fingerprint Development on Plant Leaves

A. Powdering Method

Most of the leaves are greener which makes black powder a suitable choice. Two common powdering techniques are:

• Regular powder with fingerprint brush (Non-magnetic)
• Magnetic powder with Magna brush

Development Procedure

I. Non-Magnetic Method of Developing

1. Use a fingerprint brush and dip it into a black powder pot.
2. Way off the extra powder by tapping the brush onto the pot.
3. Move the brush gently over the prints on the leaf until they become visible.
4. Dust off excess powder
5. Use clear tape to lift developed fingerprints.

II. Magnetic Method

1. Use a Magna brush with black magnetic powder.
2. Move the brush gently over the prints until they become visible.
3. Take the excess magnetic powder in the Magna brush back to the magnetic powder bottle and release it.
4. Move the empty Magna brush over the leaf so that it attracts all the extra magnetic powder.
5. Use clear tape or any hinge lifters to lift developed fingerprints.

B. Superglue (Cyanoacrylate) Fuming Method 

Superglue (Cyanoacrylate) fuming is a chemical method that uses a fume chamber for the detection of latent fingerprints on nonporous surfaces and can be used to develop fingermarks on leaves. 

This method relies on the deposition of polymerized cyanoacrylate ester on residues of latent fingerprints. By applying this method, clear stable, white-colored fingerprints can be obtained. 

References:

• Usmani & Albanese, Fingerprints found and lifted from indoor plants [ResearchPaper]
• Bunter, S., & Ffs, B. (2014). How Long Can an Identifiable Fingerprint Persist on an Exterior Surface? [ResearchPaper]
• Evaluation of latent fingermark color contrast as aging parameter under different environmental conditions: A preliminary study. De Alcaraz‐Fossoul, J., et al. (2020). [Wiley]
• Cadd, S., Islam, M., Manson, P., & Bleay, S. (2015). Fingerprint composition and aging: A literature review. Science & Justice. [ScienceDirect]