Porous surfaces- Investigators use a chemical method to locate fingerprints such as iodine fuming, silver nitrate, and ninhydrin. When one of these chemicals comes in contact with another chemical it creates a fingerprint residue so the print can become visual.

Iodine fuming takes place in a fuming chamber. This process starts by heating up solid crystal iodine that creates vapors that adhere to the oily residue in the fingerprint.

When exposed to latent prints, silver nitrate reacts with the chloride of the salt molecules found in the print residue which forms silver chloride. When that's exposed to a ultraviolet light, the silver chloride will turn black or brown which makes the print visible. This method works best on impressions left in cardboard and paper-like surfaces.

Ninhydrin is more commonly used than iodine fuming and silver nitrate techniques to locate a latent print. Ninhydrin is used by getting the object that the print is located on and dip it or spray it with the ninhydrin solution that reacts with with the oils in the print's residue and it creates a bluish print. The only bad part about using this method is that this process is very slow and it often takes several hours for the print to become visible.

Nonporous surfaces- Investigators usually use a powder technique to identify latent prints on surfaces such as glass, marble, plastic, and finished wood. When powder is put on the surface, it adheres to the residue that is deposited from the finger's touch which allows investigators to find the print.

To avoid smudging the print investigators use a magnetic powder technique. The magnetic powder is poured on the surface and spread evenly over the surface using magnetic force instead of spreading it with a brush.

Superglue fuming is a chemical process that exposes and fixes fingerprints on nonporous surfaces. This method works by using a airtight tank, also known as a fuming chamber, to heat up the super glue (liquid cyanoacrylate) that releases gases that adhere to the oily residue on the print. This process can also be performed at the crime scene.

Human skin- Locating and identifying fingerprints left on human skin is incredibly difficult. The first major hardship is finding the print since the oily residue left by fingers that create fingerprints by itself is often present on human skin which makes it extremely difficult to create contrasts between the surface of the skin and the fingerprint.

How investigators examine surfaces for fingerprints: