Methods of Collecting Footprints for Identification

1. Preserving the Original Impression: 

When a footprint is found on portable objects like mats or cardboard, transporting the entire object to the laboratory for further analysis is convenient. It's advisable to photograph the print before removal to avoid damage during transit.

2. Photography:

All footprints, whether sunken or surface marks, should be photographed. Capture three images: a top view and two angled views. Include an identification slip with case details, a foot ruler for size reference, and the investigator's initials.

3. Tracing:

Tracing is a rudimentary method for recording surface prints. Place a glass or celluloid sheet above the print, ensuring it doesn't touch. Sketch the contour along the print line, noting toe features, ball of the foot, heel, creases, cracks, and warts. Write case particulars and signatures on the glass.

4. Lifting:

When prints match the background color (e.g., blood on red or dust on white), photography may be challenging. Use black photo bromide paper for dusty or light prints and white photo bromide paper for blood-stained or dark prints. Moisten and press the paper onto the print to lift it.

5. Casting:

Casts are made from sunken footprints using materials like plaster of Paris, wax, resins, or plastic powders. Plaster of Paris is commonly used. Pour the casting material onto the impression to create a 3D representation of the print.

These collection methods ensure footprints are properly preserved and ready for forensic analysis.

Mastering the Art of Casting Footprints for Forensic Investigations:

How to Properly Cast Footprints:

Casting footprints is a meticulous process crucial for forensic investigations. Here's a step-by-step guide:

1. Prepare the Impression

Remove debris like grass or stones from the impression without disturbing it.

2. Frame It

Place a wooden or metallic frame around the impression to retain the plaster of Paris.

3. Protect the Impression

Do not apply pressure to the frame; this may damage the print.

4. Seal with Shellac

Spray a shellac solution (250gm shellac in 1L alcohol) over the impression.

Let it dry for 10-15 minutes.

5. Use a Separating Agent

Sprinkle a thin layer of talcum powder or mineral oil to separate the shellac from the cast.

6. Mix the Plaster

Combine three parts plaster of Paris with three parts water until it reaches a creamy consistency.

Maintain a 1:1 ratio.

7. Pour Carefully

Pour the plaster into an unimportant corner of the frame to avoid damage.

Let it flow slowly until it fills the impression to about 1/2 inch thick.

8. Reinforce the Cast

Add wire gauze pieces.

Pour more plaster until it reaches about one inch in thickness.

9. Allow It to Set

Let the cast set for 10-15 minutes.

10. Engrave Essential Details

Use a copying pencil to write on the cast:

Crime number, Law section, and Police Station, Exact location, Date and time, 

Recorder's name, IO's signature, Witness signatures

11. Preserve a Sample - Keep a sample of plaster of Paris and soil for obtaining test prints from suspects under similar conditions.

12. Remove the Cast - Carefully lift the cast by removing the retaining frame and gently slipping your fingers under it. - Rinse it with water to remove any adhering earth particles.

Following these steps ensures accurate and reliable casts of footprints for forensic analysis.