Fantastic Finger Forensics Fact

Okay before you get into the ease of reading my blog, take out a second and look at your thumb, thumb fingerprint. Fingerprint is a word we hear all the time and every here and there, but how much do we really know about these unique markings on our fingertips? Have you ever wondered what those swirling lines mean or denote?

I am sure that no matter what background you are from, you will enjoy reading this blog. Fingerprints, are not just for unlocking your phones, of course not, right? These swirls and twists and turns are like a personal QR code or BAR code which will be different for every different person. DNA can be more or less similar in twins, but fingerprints won’t be the same even for identical twins. An interesting fact is, that no single person is found to have the same fingerprint in different fingers. There’s a one in 64 billion chance that your fingerprint will match up exactly with someone else’s.

Fingerprints are the impression of the tiny ridges; whorls & valley patterns present on the tip of each finger. These ridges present all over the skin are developed before birth. Each person has a unique fingerprint and lasts lifelong.

Ridges are the raised lines or patterns on the surface of the skin, especially on the fingertips, palms, and soles of the feet.

In recent times, various organizations, including schools, colleges, hospitals, banks, law enforcement agencies and MNCs have the fingerprint classification system. This system uses the unique identifying feature of a person and compares that from a huge database.

Fingerprints are used by the criminal justice system to verify an identity & track their previous records. To match a print, the analyst uses the minutiae, or ridge characteristics to find the similar points to find the suspect.

Before we learn different types of fingerprints, we have to get familiarised with certain types of terminologies of minutiae patterns:

1. Ridge Ending: Simple ridges that stop without dividing into branches.
2. Island Ridge: Small ridge that is not connected to other ridges.
3. Bifurcation: Diversion of a ridge into two branches.
4. Dot or island: A tiny raised area or dot within fingerprint
5. Ridge enclosure or lake or eye: Ridges encircle a small space.
6. Bridge crossover: a ridge that connects two other ridges.
7. Delta: Y-shaped ridge where two ridges converge.
8. Core: Central area or point of the fingerprint.
9. Double bifurcation: Ridge splits into two branches & then each branch splits again.
10. Trifurcation: Diversion of a ridge into three separate branches.

Fingerprints can be classified under different types, but the main 3 types of fingerprints are:

1. Arch
2. Loop
3. Whorls

We will go into each of these types in detail.

1. Arch

- It is the simplest but the rarest type of fingerprint, found in only about 5% of all fingerprints. It is formed by ridges that enter from one side and exit on the other side of the print. No deltas or loops are present in between.

- Arch itself has 2 sub-types, that are:

a. Plain Arch?—?These lines are raised ridges that flow continuously from one side to other on the fingerprint with a gentle rise or drop at the centre. This type may feature minutiae elements like bifurcations, islands, dots etc but there will be consistency from one side of the finger to the other.

b. Tented arch?—?Similar to plain arch, these are the elevated ridges with sharper edges that flow from one direction of the print to other. A tent arch has a ‘tent-like’ shape.

2. Loops

- Loops have one delta and one or more ridges. Ridges enter & leave on the same side. These patterns are named for their positions related to the radius & ulna bones. Loops account for approx. 60% of pattern types.

- Loops also has 2 sub-types, which are:

a. Ulnar loop?—?This pattern is named after the long forearm ulna bone, that extends from the elbow to the little finger. Loops that open towards the little fingers are called ulnar loops.

b. Radial Loop?—?This pattern is named from the radius bone. The loop that opens towards the thumb is called the radial loop.

3. Whorls

- This has at least one ridge that makes a complete circuit or in other words it will have the characteristics of a core. Whorls make up approx. 35% of pattern types.

- Whorls has 4 types, that are:

a. Plain whorl?—?Simplest & most common. This pattern has a ring-shaped design that resembles a spiral type structure. This is round & continuous present at the centre.

b. Central pocket whorl?—?Advanced form of the plain whorl. In this pattern, central ridges will curve multiple times to create a smaller inner whorl.

c. Double Loop?—?As the name suggests, 2 different or distinct loops but connected loop formation. These can have one or more ridges that make a full circuit and 2 deltas.

d. Accidental whorl?—?This design combines 2 different types of patterns and has two or more deltas. This pattern either meets some of the criteria for 2 or more different types, or a becomes a pattern that doesn’t fit under any of the descriptions.

Where are Fingerprints?found?

The Answer is Everywhere! Literally Everywhere on any surface! Soft surfaces like soap, wax, paint and hard surfaces like glass, paper, laptop, knife. On hard surfaces, fingerprints can be patent, that is visible to naked eye formed by blood, ink, paint etc or they can be latent, that is invisible prints formed by the body’s natural oils & sweat on the skin.

Here a thumb rule is, the smoother & less porous a surface is, the greater the potential of any latent prints present can be found or developed.

Fingerprint Collection Methods

1. Collecting Patent Prints: This is collected by a straightforward method, that is Photographing the print in high resolution forensic measurement scale in the image.

2. Collecting Latent Prints: This is collected by dusting a smooth or non-porous surface with fingerprint powder (black granular, aluminium flake, black magnetic, etc). The lifting tape is also placed on a print for preservation.

3. Alternate Light Source (ALS): It is used to examine any likely surfaces like doors, windows, railings etc. This has a laser or LED device that emits a particular wavelength or spectrum of light. Then they are photographed, collected and preserved.

4. Cyanoacrylate: Also known as superglue, used before applying powders or dye stains.

5. Chemical Developers: Porous surfaces like papers are processed to find the fingerprints. Chemicals like ninhydrin are used to get latent fingerprints. Ninhydrin causes prints to turn into purple colour, which can be easily located & photographed.

How is Fingerprint analysed?

Fingerprint analysis is conducted by law enforcement agencies or crime laboratories. The examiner uses the ACE-V method to analyse any print.

ACE-V is Analysis, Comparison, Evaluation & Verification

1. Analysis- This step determines whether the print will go for comparison or not. If the print is not collected properly or tampered with or has inadequate quality then it is marked as not suitable evidence otherwise the print is properly analysed and sent for comparison.
2. Comparisons?—?In this stage, the collected and analysed prints are compared from the previous databases such as the FBI’s Integrated Automated Fingerprint Identification System (IAFIS) which has more than 72 million print records from criminals, military personnel, government employees, etc.
3. Evaluation: Here the examiner finalizes that the prints are from the identified source and of the identified person or it is from a different source or it’s inclusive (Maybe cause of improper collection, inadequate quality or improper analysis).
4. Verification: This is handled by another examiner who analyses, compares and evaluates the conclusion to support the final report and testifies in court.

Limitations of Fingerprint analysis:

1. There must be the known print in the database for comparison, otherwise, the unknown print won’t make sense unless there is a known suspect.
2. Fingerprints cannot determine the time period. This means if we get a latent fingerprint, as an examiner we can’t say at what range of time period the fingerprint would have been deposited.
3. Fingerprints cannot determine age, sex, or race from a latent print if there is no sufficient amount of DNA present along with it.

Writing a blog related to Biology and Forensics is like revisiting my bio roots. It’s so cool & fascinating, how the details we learn in biology have applications in cybersecurity.

Happy Reading!! ??