Fingerprint analysis has been used to identify suspects and solve crimes for more than 100 years, and it remains an extremely valuable tool for law enforcement. One of the most important uses for fingerprints is to help investigators link one crime scene to another involving the same person. Also, it is proven by different studies and researches that no two people have exactly the same fingerprints. Even identical twins, with identical DNA, have different fingerprints. This uniqueness allows fingerprints to be used in all sorts of ways, including for background checks, biometric security, mass disaster identification, and of course, in criminal investigations.
Collection and Preservation of Latent & Patent Fingerprints:Patent fingerprintsare those which are visible to naked eye. Latent fingerprints are invisible to naked eye. It is developed by various developing techniques like iodine chamber, cyno-acrylate, etc. to make it visible. A patent fingerprint is already visible and is usually just photographed. The photographs of the fingerprints help them to be preserved for long time.
Some of the methods used for developing latent prints are:
Dusting or Staining:This is when forensic expert “dust” prints by gently applying aluminum flakes or other granular powder to a surface. The powder bonds with the oils that create a print, revealing and defining a print. Professionals might choose to use dye stains instead of powders. They may also apply a sort of glue called cyanoacrylate before dusting or staining to better preserve the print, which is then photographed and transferred to a special card using an adhesive tape.
Alternate Light Source (ALS):Alternative Light Source print analysis uses LED lights or special lasers to reveal prints on certain surfaces. Experts can use special dyes and dust (often with cyanoacrylate), camera filters, and photo processing technologies to then capture the print for analysis.
Chemical Developers:Latent fingerprints on certain surfaces, like paper or porous materials, can be difficult to lift with dust or dyes. In these cases, professionals use chemical developers that interact with amino acids and other natural residue to reveal latent prints by either coloring them or making them visible under certain lights. For example, Ninhydrin method, Iodine Fuming method etc.
Analysis and Comparison:The collected/developed printsare identified and as loops, whorls, and arches that make up its unique pattern and to discern whether the quality or amount of the pattern is sufficient for further examination. The analyst’s also identify scars or other features that could distinguish one person from another. In the next step of fingerprint analysis &comparison the examiner comparesthe collected fingerprints with potential matches in order to make a positive identification.