Why is paper used instead of plastic for biological evidence?

Paper allows residual moisture to escape. Sealed in plastic, a damp stain grows bacteria and mould within days, which degrades DNA and can make the sample unusable.

How should fire debris be packaged?

In a clean unlined metal can or a nylon-11 evidence bag, filled to about two thirds and sealed immediately. Polythene bags and paper both let accelerant vapour escape, which loses the very trace being sought.

What should be done with a seized phone or computer?

Document the power state and isolate it from all networks, using a Faraday bag or equivalent. If it is off, leave it off. If it is on, consult a specialist before touching it, because both shutting down and leaving it running destroy different evidence.

Why should a suspect tool never be fitted into a toolmark?

Fitting the tool creates fresh marks that contaminate the original, destroying the comparison. The mark is cast or the object seized, and the comparison is made under controlled conditions in the laboratory.

What is a control sample and why is it collected?

An unaffected reference from the same source, such as clean substrate beside a stain or undamaged paint from the same panel. It lets the laboratory distinguish the questioned material from the background it came from.

Nyayik VigyanForensic · Crime · Justice

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Crime Scene · Tools

Evidence Collection Reference

Quick reference for packaging, preserving, and labelling physical evidence.

21 of 21 entries

Liquid blood (from a person)
Biological
Container
Sterile vacuum tube with EDTA anticoagulant, sealed and labelled.
Preservation
Refrigerate at 4 °C and submit as soon as possible.
Do not
Do not freeze whole blood; it lyses the cells. Never leave it warm.
Dried bloodstain
Biological
Container
Cut out the stained substrate, or swab with a lightly moistened sterile swab. Package in paper.
Preservation
Air-dry completely before packaging. Keep cool and dark.
Do not
No plastic or airtight bags: retained moisture grows mould and destroys DNA.
Buccal or touch DNA swab
Biological
Container
Swab box or paper envelope that lets air pass.
Preservation
Air-dry, then store cool. Change gloves between every sample.
Do not
Do not breathe, talk, or sneeze over the swab. No plastic tubes wet.
Semen or other body fluid stain
Biological
Container
Paper bag or envelope; the whole garment if it is portable.
Preservation
Air-dry at room temperature away from sunlight, then package.
Do not
No heat drying and no plastic. Do not fold through the stain.
Hair
Trace
Container
Paper bindle inside a labelled envelope.
Preservation
Keep the root intact; note whether it was pulled or shed.
Do not
Do not use adhesive tape directly on the root end.
Fibres and textile debris
Trace
Container
Paper bindle, or tape lift on a clear acetate sheet.
Preservation
Package each surface separately to preserve association.
Do not
Avoid shaking the garment; it dislodges the very trace you want.
Glass fragments
Trace
Container
Rigid box or vial with padding, fragments separated.
Preservation
Keep the fracture edges intact for physical fit and note inside/outside surfaces.
Do not
Do not let fragments rub together; edge damage destroys fit evidence.
Paint chips and smears
Trace
Container
Paper bindle in a rigid container.
Preservation
Collect a control sample from an undamaged area of the same object.
Do not
Do not scrape layers apart; layer sequence is the evidence.
Soil and mineral debris
Trace
Container
Clean airtight glass or plastic jar.
Preservation
Collect control samples at intervals from the scene for comparison.
Do not
Do not dry or sieve before submission.
Firearm
Firearms
Container
Unload, secure the action, and box with the weapon tied down. Note the chamber and cylinder positions first.
Preservation
Preserve any residue or trace on the muzzle and grip; handle by textured areas.
Do not
Do not insert anything into the barrel and never dry-fire it.
Cartridge cases and bullets
Firearms
Container
Separate paper envelopes or padded vials, one per item.
Preservation
Record the position of each item before recovery.
Do not
Do not mark the case head, base, or bearing surface; those carry toolmarks.
Gunshot residue (hands)
Firearms
Container
Adhesive stub or swab kit, sealed per kit instructions.
Preservation
Sample as early as possible; residue is lost within hours.
Do not
Do not let the subject wash their hands or handle other surfaces.
Fire debris and accelerant
Chemical
Container
Clean unlined metal can, or a nylon-11 evidence bag.
Preservation
Fill to about two thirds and seal immediately; keep cool.
Do not
Never polythene bags or paper: volatiles diffuse straight through and the result is lost.
Suspected drugs
Chemical
Container
Heat-sealed tamper-evident bag; keep original packaging separately.
Preservation
Weigh and photograph before sealing. Maintain a strict chain of custody.
Do not
Do not field-taste or open near other exhibits; cross-contamination is fatal.
Toxicology samples (post-mortem)
Chemical
Container
Preservative tubes: sodium fluoride for alcohol, plain for most drugs. Separate blood, urine, vitreous, liver.
Preservation
Refrigerate or freeze per laboratory instruction; label the site of collection.
Do not
Do not pool sites into one container.
Questioned document
Documents
Container
Flat manila envelope or transparent sleeve, unfolded.
Preservation
Handle at the edges with gloves. Keep away from light and humidity.
Do not
No new folds, staples, paper clips, or writing on it. Never test with solvents.
Latent fingerprint lift
Impression
Container
Backing card in an envelope, one lift per card.
Preservation
Record surface, location, and orientation on the card immediately.
Do not
Do not stack lifts face to face.
Footwear or tyre impression
Impression
Container
Cast in dental stone once set, in a rigid box; plus a scaled photograph.
Preservation
Photograph with oblique lighting and a scale before casting. Let the cast cure fully.
Do not
Do not clean the cast on scene; laboratory removes soil under control.
Toolmark and the suspect tool
Impression
Container
Package tool and marked object separately, working surfaces protected.
Preservation
Cast the mark if the object cannot be moved.
Do not
Never fit the tool into the mark to test it; that creates fresh marks and destroys the comparison.
Computer, phone, or storage device
Digital
Container
Faraday bag or signal-shielded container; box for the device.
Preservation
Document the power state. If off leave it off; if on, consult a specialist before touching it. Capture the screen and seize chargers.
Do not
Do not power on, browse, or connect it. Do not let it reach a network; remote wipe is real.
Entomological samples
Biological
Container
Two sets: one killed in hot water then preserved in 80% ethanol, one live in a breathable container with substrate.
Preservation
Record ambient and body temperatures plus the collection site on the body.
Do not
Do not preserve every specimen; the live set is needed for rearing.

A study and revision aid. Packaging requirements vary by jurisdiction and by the receiving laboratory, and the laboratory's own submission manual always takes precedence. Follow your agency's standard operating procedure for anything that will be used in evidence.

How the evidence collection reference works

Most evidence is lost before it reaches a laboratory, and packaging is usually the reason. The governing principle is simple: anything biological needs to breathe, anything volatile must be sealed vapour-tight, and anything digital must be isolated from a network.

Dried biological evidence goes into paper because retained moisture grows mould and destroys DNA. Fire debris goes into unlined metal cans or nylon bags because accelerant vapour diffuses straight through polythene. A phone goes into a Faraday bag because a remote wipe takes seconds. Each entry here gives the container, the preservation step, and the mistake that ruins the exhibit.

Frequently asked questions

Why is paper used instead of plastic for biological evidence?: Paper allows residual moisture to escape. Sealed in plastic, a damp stain grows bacteria and mould within days, which degrades DNA and can make the sample unusable.
How should fire debris be packaged?: In a clean unlined metal can or a nylon-11 evidence bag, filled to about two thirds and sealed immediately. Polythene bags and paper both let accelerant vapour escape, which loses the very trace being sought.
What should be done with a seized phone or computer?: Document the power state and isolate it from all networks, using a Faraday bag or equivalent. If it is off, leave it off. If it is on, consult a specialist before touching it, because both shutting down and leaving it running destroy different evidence.
Why should a suspect tool never be fitted into a toolmark?: Fitting the tool creates fresh marks that contaminate the original, destroying the comparison. The mark is cast or the object seized, and the comparison is made under controlled conditions in the laboratory.
What is a control sample and why is it collected?: An unaffected reference from the same source, such as clean substrate beside a stain or undamaged paint from the same panel. It lets the laboratory distinguish the questioned material from the background it came from.

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Crime Scene · Tools

Evidence Collection Reference

Quick reference for packaging, preserving, and labelling physical evidence.

21 of 21 entries

Liquid blood (from a person)
Biological
Container
Sterile vacuum tube with EDTA anticoagulant, sealed and labelled.
Preservation
Refrigerate at 4 °C and submit as soon as possible.
Do not
Do not freeze whole blood; it lyses the cells. Never leave it warm.
Dried bloodstain
Biological
Container
Cut out the stained substrate, or swab with a lightly moistened sterile swab. Package in paper.
Preservation
Air-dry completely before packaging. Keep cool and dark.
Do not
No plastic or airtight bags: retained moisture grows mould and destroys DNA.
Buccal or touch DNA swab
Biological
Container
Swab box or paper envelope that lets air pass.
Preservation
Air-dry, then store cool. Change gloves between every sample.
Do not
Do not breathe, talk, or sneeze over the swab. No plastic tubes wet.
Semen or other body fluid stain
Biological
Container
Paper bag or envelope; the whole garment if it is portable.
Preservation
Air-dry at room temperature away from sunlight, then package.
Do not
No heat drying and no plastic. Do not fold through the stain.
Hair
Trace
Container
Paper bindle inside a labelled envelope.
Preservation
Keep the root intact; note whether it was pulled or shed.
Do not
Do not use adhesive tape directly on the root end.
Fibres and textile debris
Trace
Container
Paper bindle, or tape lift on a clear acetate sheet.
Preservation
Package each surface separately to preserve association.
Do not
Avoid shaking the garment; it dislodges the very trace you want.
Glass fragments
Trace
Container
Rigid box or vial with padding, fragments separated.
Preservation
Keep the fracture edges intact for physical fit and note inside/outside surfaces.
Do not
Do not let fragments rub together; edge damage destroys fit evidence.
Paint chips and smears
Trace
Container
Paper bindle in a rigid container.
Preservation
Collect a control sample from an undamaged area of the same object.
Do not
Do not scrape layers apart; layer sequence is the evidence.
Soil and mineral debris
Trace
Container
Clean airtight glass or plastic jar.
Preservation
Collect control samples at intervals from the scene for comparison.
Do not
Do not dry or sieve before submission.
Firearm
Firearms
Container
Unload, secure the action, and box with the weapon tied down. Note the chamber and cylinder positions first.
Preservation
Preserve any residue or trace on the muzzle and grip; handle by textured areas.
Do not
Do not insert anything into the barrel and never dry-fire it.
Cartridge cases and bullets
Firearms
Container
Separate paper envelopes or padded vials, one per item.
Preservation
Record the position of each item before recovery.
Do not
Do not mark the case head, base, or bearing surface; those carry toolmarks.
Gunshot residue (hands)
Firearms
Container
Adhesive stub or swab kit, sealed per kit instructions.
Preservation
Sample as early as possible; residue is lost within hours.
Do not
Do not let the subject wash their hands or handle other surfaces.
Fire debris and accelerant
Chemical
Container
Clean unlined metal can, or a nylon-11 evidence bag.
Preservation
Fill to about two thirds and seal immediately; keep cool.
Do not
Never polythene bags or paper: volatiles diffuse straight through and the result is lost.
Suspected drugs
Chemical
Container
Heat-sealed tamper-evident bag; keep original packaging separately.
Preservation
Weigh and photograph before sealing. Maintain a strict chain of custody.
Do not
Do not field-taste or open near other exhibits; cross-contamination is fatal.
Toxicology samples (post-mortem)
Chemical
Container
Preservative tubes: sodium fluoride for alcohol, plain for most drugs. Separate blood, urine, vitreous, liver.
Preservation
Refrigerate or freeze per laboratory instruction; label the site of collection.
Do not
Do not pool sites into one container.
Questioned document
Documents
Container
Flat manila envelope or transparent sleeve, unfolded.
Preservation
Handle at the edges with gloves. Keep away from light and humidity.
Do not
No new folds, staples, paper clips, or writing on it. Never test with solvents.
Latent fingerprint lift
Impression
Container
Backing card in an envelope, one lift per card.
Preservation
Record surface, location, and orientation on the card immediately.
Do not
Do not stack lifts face to face.
Footwear or tyre impression
Impression
Container
Cast in dental stone once set, in a rigid box; plus a scaled photograph.
Preservation
Photograph with oblique lighting and a scale before casting. Let the cast cure fully.
Do not
Do not clean the cast on scene; laboratory removes soil under control.
Toolmark and the suspect tool
Impression
Container
Package tool and marked object separately, working surfaces protected.
Preservation
Cast the mark if the object cannot be moved.
Do not
Never fit the tool into the mark to test it; that creates fresh marks and destroys the comparison.
Computer, phone, or storage device
Digital
Container
Faraday bag or signal-shielded container; box for the device.
Preservation
Document the power state. If off leave it off; if on, consult a specialist before touching it. Capture the screen and seize chargers.
Do not
Do not power on, browse, or connect it. Do not let it reach a network; remote wipe is real.
Entomological samples
Biological
Container
Two sets: one killed in hot water then preserved in 80% ethanol, one live in a breathable container with substrate.
Preservation
Record ambient and body temperatures plus the collection site on the body.
Do not
Do not preserve every specimen; the live set is needed for rearing.

How the evidence collection reference works

Frequently asked questions

Why is paper used instead of plastic for biological evidence?: Paper allows residual moisture to escape. Sealed in plastic, a damp stain grows bacteria and mould within days, which degrades DNA and can make the sample unusable.
How should fire debris be packaged?: In a clean unlined metal can or a nylon-11 evidence bag, filled to about two thirds and sealed immediately. Polythene bags and paper both let accelerant vapour escape, which loses the very trace being sought.
What should be done with a seized phone or computer?: Document the power state and isolate it from all networks, using a Faraday bag or equivalent. If it is off, leave it off. If it is on, consult a specialist before touching it, because both shutting down and leaving it running destroy different evidence.
Why should a suspect tool never be fitted into a toolmark?: Fitting the tool creates fresh marks that contaminate the original, destroying the comparison. The mark is cast or the object seized, and the comparison is made under controlled conditions in the laboratory.
What is a control sample and why is it collected?: An unaffected reference from the same source, such as clean substrate beside a stain or undamaged paint from the same panel. It lets the laboratory distinguish the questioned material from the background it came from.

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Evidence Collection Reference

Liquid blood (from a person)

Dried bloodstain

Buccal or touch DNA swab

Semen or other body fluid stain

Hair

Fibres and textile debris

Glass fragments

Paint chips and smears

Soil and mineral debris

Firearm

Cartridge cases and bullets

Gunshot residue (hands)

Fire debris and accelerant

Suspected drugs

Toxicology samples (post-mortem)

Questioned document

Latent fingerprint lift

Footwear or tyre impression

Toolmark and the suspect tool

Computer, phone, or storage device

Entomological samples

How the evidence collection reference works

Frequently asked questions

Other forensic tools

Calibrating

Evidence Collection Reference

Liquid blood (from a person)

Dried bloodstain

Buccal or touch DNA swab

Semen or other body fluid stain

Hair

Fibres and textile debris

Glass fragments

Paint chips and smears

Soil and mineral debris

Firearm

Cartridge cases and bullets

Gunshot residue (hands)

Fire debris and accelerant

Suspected drugs

Toxicology samples (post-mortem)

Questioned document

Latent fingerprint lift

Footwear or tyre impression

Toolmark and the suspect tool

Computer, phone, or storage device

Entomological samples

How the evidence collection reference works

Frequently asked questions

Other forensic tools